Zoom lens system having an image blur compensating function

ABSTRACT

A zoom lens system has the first to fifth lens units from the object side. Refractive powers of the first to fifth lens units are positive, negative, negative, positive, negative, respectively. During zooming, the distances between the lens units are varied. Image blur compensation is made by parallel decentering the second lens unit. The second lens unit includes a first lens unit and a rear lens unit, either of which can be moved vertically to the optical axis to compensate for image blur. The distance between the front and rear lens units is fixed during a zooming mode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system having an image blurcompensating function, and more specifically, to a zoom lens systemsuitable for use as a telephoto zoom lens and a standard/standardhigh-magnification zoom lens system for single-lens reflex cameras anddigital cameras capable of preventing image blurring caused by vibrationof an image plane (e.g. vibration of an image plane caused by camerashake when photo-graphing is performed with the camera held in hands).

2. Description of the Prior Art

Conventionally, unsuccessful photography resulted mostly from camerashake and failure in focusing. In recent years, however, most camerashave adopted the autofocus mechanism and the focusing accuracy of theautofocus mechanism has improved, so that the failure in focusing ishardly a cause of unsuccessful photography. On the other hand, thestandard lens system mounted in cameras has been shifted from the fixedfocal length lens system to the zoom lens system and the focal length atthe telephoto limit and the magnification have been increasedaccordingly, so that image blur resulting from camera shake is verylikely caused. Consequently, it is no exaggeration to say thatunsuccessful photography results from camera shake. For this reason, animage blur compensating function is indispensable to taking opticalsystems.

As the zoom lens system having an image blur compensating function,various types have been known. For example, Japanese Laid-open PatentApplication No. H6-337375 discloses a telephoto zoom lens systemcomprising five lens units of positive, negative, negative, positive,negative configuration or positive, negative, positive, positive,negative configuration wherein image blur compensation is made by movingthe entire second lens unit vertically (i.e. in a directionperpendicular) to the optical axis. Japanese Laid-open PatentApplication No. H5-232410 discloses a telephoto zoom lens systemcomprising four lens units of positive, negative, positive, positiveconfiguration wherein image blur compensation is made by moving theentire second lens unit vertically to the optical axis. As acommercially available zoom lens system having an image blurcompensating function, a zoom lens system is known comprising six lensunits of positive, negative, positive, negative, positive, negativeconfiguration wherein image blur compensation is made by moving theentire second lens unit vertically to the optical axis.

However, the above-described conventional zoom lens systems having animage blur compensating function are defective since the total length istoo long at the wide angle limit and at the telephoto limit. Even thougha zoom lens system has an image blur compensating function, it isundesirable if the lens system is large in size compared with a zoomlens system having no image blur compensating function because the useof such a large-size lens system is disadvantageous in improvingportability and handiness. In the zoom lens system having an image blurcompensating function, not only the optical quality is necessarilyexcellent in a normal condition (hereinafter, referred to as“pre-decentering condition”) but also the optical quality is necessarilymaintained excellent in a compensated condition (hereinafter, referredto as “post-decentering condition”) by preventing aberrations from beingcaused by the decentering of the lens (hereinafter, aberrations causedby decentering will be referred to as “decentering aberrations”).

As the taking optical system having an image blur compensating function,various other types have also been proposed. For example, JapaneseLaid-open Patent Application No. H5-224160 discloses a zoom lens systemcomprising five lens units of positive, negative, positive, positive,negative configuration wherein the fifth lens unit is divided into afront lens unit having a negative refractive power and a rear lens unithaving a positive refractive power and image blur compensation is madeby moving the front lens unit having a negative refractive powervertically to the optical axis. Japanese Laid-open Patent ApplicationNo. H7-199124 and U.S. Pat. No. 5,585,966 disclose a zoom lens systemcomprising four lens units of positive, negative, positive, positiveconfiguration wherein image blur compensation is made by moving theentire third lens unit vertically to the optical axis. JapaneseLaid-open Patent Application No. H2-135408 discloses a telephoto lenssystem comprising four lens units of positive, negative, positive,negative configuration wherein image blur compensation is made by movingthe entire second lens unit or the entire third lens unit vertically tothe optical axis. Japanese Laid-open Patent Application No. H6-289298discloses a zoom lens system comprising four lens units of positive,negative, positive, positive configuration wherein image blurcompensation is made by moving the entire second lens unit vertically tothe optical axis.

In the zoom lens systems disclosed in Japanese Laid-open PatentApplications No. H5-232410, No. H5-224160 and No. H6-289298 whereinimage blur compensation is made by moving a plurality of lensesvertically to the optical axis, the weight of the moved lenses is heavyand the lens frames for holding them are large, so that the drivingsystem for driving image blur compensation is greatly burdened. Thisresults in an increase in size of the image blur compensation drivingsystem and a delay in response to decentering. Additionally, in the zoomlens system disclosed in Japanese Laid-open Patent Application No.H5-224160, since the fifth lens unit is largely moved during zooming, itis necessary to largely move the heavy image blur compensation drivingsystem during zooming, so that the moving means for zooming is largelyburdened. Since the difference in image blur compensation movementamount between at the wide-angle limit and at the telephoto limit isgreat, the accuracy of calculating the image blur compensation movementamount degrades.

In the zoom lens system disclosed in Japanese Laid-open PatentApplication No. H7-199124 wherein image blur compensation is made bymoving the entire third lens unit, since the third lens unit is formedof one doublet lens, the lens moved for image blur compensation is lightin weight. However, since the degree of freedom of aberration correctionof one doublet lens is too low, it is impossible for the third lens unitto largely contribute to zooming, so that the optical system excessivelyincreases in size. Since the overall size is great, the optical systemis, although suitable for use as the taking optical system for videocameras, too large in size for use as the standard zoom taking opticalsystem for single lens reflex cameras and compactness is lost.

In the zoom lens system disclosed in Japanese Laid-open PatentApplication No. H6-337375, since image blur compensation is made bymoving one doublet lens, the lens moved for image blur compensation islight in weight. However, since the angles of view used are biasedtoward the telephoto side, the optical system is too large in size foruse as the standard zoom lens system.

In the zoom lens systems disclosed in Japanese Laid-open PatentApplications No. H5-232410 and No. H7-199124, since the angles of viewused are biased toward the telephoto side, the optical system is toolarge in size for use as the standard zoom lens system. In JapaneseLaid-open Patent Application No. H2-135408, since the disclosed opticalsystem is a fixed focal length lens system, its arrangement for imageblur compensation does not fulfill the recent requirements for the zoomlens system having an image blur compensating function.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a zoom lens systemhaving an image blur compensating function being short in total lengthand compact, wherein aberrations are excellently corrected in both thenormal and compensated conditions.

Another object of the present invention is to provide a zoom lens systemhaving an image blur compensating function where the lens unit moved forimage blur compensation is light in weight.

To achieve the above-mentioned objects, a zoom lens system having animage blur compensating function according to the present invention isprovided with, from the object side, a first lens unit having a positiverefractive power and a second lens unit having a negative refractivepower, wherein zooming is performed by varying the distances between thelens units. The first lens unit is moved toward the object side duringzooming from the wide-angle limit to the telephoto limit. Image blurcompensation is made by moving a part of any of the second lens unit andsucceeding lens units vertically to the optical axis.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other objects and features of this invention will become clearfrom the following description, taken in conjunction with the preferredembodiments with reference to the accompanied drawings in which:

FIGS. 1A to 1D are views of assistance in explaining a cause of imagedegradation of an image blur compensating optical system;

FIGS. 2A and 2B are views of assistance in explaining the relationshipbetween the optical system and the coordinates;

FIGS. 3A and 3B are views of assistance in explaining the difference inlight passage position caused by decentering;

FIG. 4 is a view of assistance in explaining the rotational conversionof the object plane;

FIG. 5 is a view of assistance in explaining the aberration coefficientsof reversed and non-reversed optical systems;

FIGS. 6A and 6B are views of assistance in explaining the rotationalconversion;

FIG. 7 is a view of assistance in explaining the conversion to the imageplane;

FIG. 8 shows the lens arrangement of a first embodiment;

FIGS. 9A to 9I show longitudinal aberration curves of the firstembodiment before decentering;

FIGS. 10A to 10E show meridional lateral aberration curves of the firstembodiment at the wide angle limit before and after decentering;

FIGS. 11A to 11E show meridional lateral aberration curves of the firstembodiment at the telephoto limit before and after decentering;

FIG. 12 shows the lens arrangement of a second embodiment;

FIGS. 13A to 13I show longitudinal aberration curves of the secondembodiment before decentering;

FIGS. 14A to 14E show meridional lateral aberration curves of the secondembodiment at the wide angle limit before and after decentering;

FIGS. 15A to 15E show meridional lateral aberration curves of the secondembodiment at the telephoto limit before and after decentering;

FIG. 16 shows the lens arrangement of a third embodiment;

FIGS. 17A to 17I show longitudinal aberration curves of the thirdembodiment before decentering;

FIGS. 18A to 18E show meridional lateral aberration curves of the thirdembodiment at the wide angle limit before and after decentering;

FIGS. 19A to 19E show meridional lateral aberration curves of the thirdembodiment at the telephoto limit before and after decentering;

FIG. 20 shows the lens arrangement of a fourth embodiment;

FIGS. 21A to 21I show longitudinal aberration curves of the fourthembodiment before decentering;

FIGS. 22A to 22E show meridional lateral aberration curves of the fourthembodiment at the wide angle limit before and after decentering;

FIGS. 23A to 23E show meridional lateral aberration curves of the fourthembodiment at the telephoto limit before and after decentering;

FIG. 24 shows the lens arrangement of a fifth embodiment;

FIGS. 25A to 25I show longitudinal aberration curves of the fifthembodiment before decentering;

FIGS. 26A to 26E show meridional lateral aberration curves of the fifthembodiment at the wide angle limit before and after decentering;

FIGS. 27A to 27E show meridional lateral aberration curves of the fifthembodiment at the telephoto limit before and after decentering;

FIG. 28 shows the lens arrangement of a sixth embodiment;

FIGS. 29A to 29I show longitudinal aberration curves of the sixthembodiment before decentering;

FIGS. 30A to 30E show meridional lateral aberration curves of the sixthembodiment at the wide angle limit before and after decentering;

FIGS. 31A to 31E show meridional lateral aberration curves of the sixthembodiment at the telephoto limit before and after decentering;

FIG. 32 shows the lens arrangement of a seventh embodiment;

FIGS. 33A to 33I show longitudinal aberration curves of the seventhembodiment before decentering;

FIGS. 34A to 34E show meridional lateral aberration curves of theseventh embodiment at the wide angle limit before and after decentering;

FIGS. 35A to 35E show meridional lateral aberration curves of theseventh embodiment at the telephoto limit before and after decentering;

FIG. 36 shows the lens arrangement of an eighth embodiment;

FIGS. 37A to 37I show longitudinal aberration curves of the eighthembodiment before decentering;

FIGS. 38A to 38E show meridional lateral aberration curves of the eighthembodiment at the wide angle limit before and after decentering;

FIGS. 39A to 39E show meridional lateral aberration curves of the eighthembodiment at the telephoto limit before and after decentering;

FIG. 40 shows the lens arrangement of a ninth embodiment;

FIGS. 41A to 41I show longitudinal aberration curves of the ninthembodiment before decentering;

FIGS. 42A to 42E show meridional lateral aberration curves of the ninthembodiment at the wide angle limit before and after decentering;

FIGS. 43A to 43E show meridional lateral aberration curves of the ninthembodiment at the telephoto limit before and after decentering;

FIG. 44 shows the lens arrangement of a tenth embodiment;

FIGS. 45A to 45I show longitudinal aberration curves of the tenthembodiment before decentering;

FIGS. 46A to 46E show meridional lateral aberration curves of the tenthembodiment at the wide angle limit before and after decentering;

FIGS. 47A to 47E show meridional lateral aberration curves of the tenthembodiment at the telephoto limit before and after decentering;

FIG. 48 shows the lens arrangement of an eleventh embodiment;

FIGS. 49A to 49I show longitudinal aberration curves of the eleventhembodiment before decentering;

FIGS. 50A to 50E show meridional lateral aberration curves of theeleventh embodiment at the wide angle limit before and afterdecentering;

FIGS. 51A to 51E show meridional lateral aberration curves of theeleventh embodiment at the telephoto limit before and after decentering;

FIG. 52 shows the lens arrangement of a twelfth embodiment;

FIGS. 53A to 53I show longitudinal aberration curves of the twelfthembodiment before decentering;

FIGS. 54A to 54E show meridional lateral aberration curves of thetwelfth embodiment at the wide angle limit before and after decentering;

FIGS. 55A to 55E show meridional lateral aberration curves of thetwelfth embodiment at the telephoto limit before and after decentering;

FIG. 56 shows the lens arrangement of a thirteenth embodiment;

FIGS. 57A to 57I show longitudinal aberration curves of the thirteenthembodiment before decentering;

FIGS. 58A to 58E show meridional lateral aberration curves of thethirteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 59A to 59E show meridional lateral aberration curves of thethirteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 60 shows the lens arrangement of a fourteenth embodiment;

FIGS. 61A to 61I show longitudinal aberration curves of the fourteenthembodiment before decentering;

FIGS. 62A to 62E show meridional lateral aberration curves of thefourteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 63A to 63E show meridional lateral aberration curves of thefourteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 64 shows the lens arrangement of a fifteenth embodiment;

FIGS. 65A to 65I show longitudinal aberration curves of the fifteenthembodiment before decentering;

FIGS. 66A to 66E show meridional lateral aberration curves of thefifteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 67A to 67E show meridional lateral aberration curves of thefifteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 68 shows the lens arrangement of a sixteenth embodiment;

FIGS. 69A to 69I show longitudinal aberration curves of the sixteenthembodiment before decentering;

FIGS. 70A to 70E show meridional lateral aberration curves of thesixteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 71A to 71E show meridional lateral aberration curves of thesixteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 72 shows the lens arrangement of a seventeenth embodiment;

FIGS. 73A to 73I show longitudinal aberration curves of the seventeenthembodiment before decentering;

FIGS. 74A to 74E show meridional lateral aberration curves of theseventeenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 75A to 75E show meridional lateral aberration curves of theseventeenth embodiment at the telephoto limit before and afterdecentering;

FIG. 76 shows the lens arrangement of an eighteenth embodiment;

FIGS. 77A to 77I show longitudinal aberration curves of the eighteenthembodiment before decentering;

FIGS. 78A to 78E show meridional lateral aberration curves of theeighteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 79A to 79E show meridional lateral aberration curves of theeighteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 80 shows the lens arrangement of a nineteenth embodiment;

FIGS. 81A to 81I show longitudinal aberration curves of the nineteenthembodiment before decentering;

FIGS. 82A to 82E show meridional lateral aberration curves of thenineteenth embodiment at the wide angle limit before and afterdecentering;

FIGS. 83A to 83E show meridional lateral aberration curves of thenineteenth embodiment at the telephoto limit before and afterdecentering;

FIG. 84 shows the lens arrangement of a twentieth embodiment;

FIGS. 85A to 85I show longitudinal aberration curves of the twentiethembodiment before decentering;

FIGS. 86A to 86E show meridional lateral aberration curves of thetwentieth embodiment at the wide angle limit before and afterdecentering;

FIGS. 87A to 87E show meridional lateral aberration curves of thetwentieth embodiment at the telephoto limit before and afterdecentering;

FIG. 88 shows the lens arrangement of a twenty-first embodiment;

FIGS. 89A to 89I show longitudinal aberration curves of the twenty-firstembodiment before decentering;

FIGS. 90A to 90E show meridional lateral aberration curves of thetwenty-first embodiment at the wide angle limit before and afterdecentering;

FIGS. 91A to 91E show meridional lateral aberration curves of thetwenty-first embodiment at the telephoto limit before and afterdecentering;

FIG. 92 shows the lens arrangement of a twenty-second embodiment;

FIGS. 93A to 93I show longitudinal aberration curves of thetwenty-second embodiment before decentering;

FIGS. 94A to 94E show meridional lateral aberration curves of thetwenty-second embodiment at the wide angle limit before and afterdecentering; and

FIGS. 95A to 95E show meridional lateral aberration curves of thetwenty-second embodiment at the telephoto limit before and afterdecentering.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, zoom lens systems having an image blur compensatingfunction embodying the present invention will be described withreference to the drawings.

<Decentering Aberration and Decentering Aberration Coefficient>

First, the definition of aberration degradation of the optical systemhaving an image blur compensating function (hereinafter, referred to as“image blur compensating optical system”) like the zoom lens systemsaccording to the present invention will be described with reference toFIGS. 1A to 1D. The decentering aberrations (off-axial image point shifterror, one-side blur, axial coma, and axial lateral chromaticaberration) shown in the figures cause the image degradation of theimage blur compensating optical system.

[Off-axial Image Point Shift Error] (FIG. 1A)

In decentered optical systems, distortion error is caused in addition tothe normal distortion. For this reason, in the image blur compensatingoptical system, when compensation is made so that the axial image point(i.e. image point in the center of the image plane) is completelymaintained stationary, the off-axial image point is not completelystationary, so that image blurring is caused. In FIG. 1A, 1 is a filmimage plane, 2 is the image point in the compensated condition(post-decentering condition), 3 is the image point in the normalcondition (pre-decentering condition), and 4 represents the direction ofimage blur compensation.

The following expression (a) holds when the optical axis is in thedirection of the X-axis, the direction of image blur is the direction ofthe Y-axis (i.e. the image blur compensation direction 4 is also thedirection of the Y-axis), and Y(y′, z′, θ) is the y coordinates {Y(0, 0,θ)=0 always holds because compensation is made so that the axial imagepoint is completely maintained stationary} of the actual image point ofa light ray with a paraxial image point of (y′, z′) at a correctionangle θ:

 ΔY(y′, z′, θ)=Y(y′, z′, θ)−Y(y′, z′, 0)  (a)

Unless otherwise specified, an off-axial image point shift error ΔY_(Y)′with respect to the image point on the Y-axis and an off-axial imagepoint shift error ΔY_(Z)′ with respect to the image point on the Z-axisare represented by the following expressions (b) and (c):

ΔY_(Y)′={ΔY(0.7field, 0, 0.7°)+ΔY(−0.7field, 0, 0.7°)}/2  (b)

ΔY_(Z)′=ΔY(0, 0.7field, 0.7°)  (c)

Here, 0.7field is approximately 12 mm for the 24 mm film according tothe new photographic standards.

[One-side Blur] (FIG. 1B)

In FIG. 1B, 5 is an image plane asymmetrical with respect to the opticalaxis AX and 6 is an image plane symmetrical with respect to the opticalaxis AX. Because of the asymmetry of the optical system, the image plane5 is asymmetrical with respect to the optical axis AX. A meridionalone-side blur ΔM′ and a sagittal one side blur ΔS′ caused by theasymmetry of the image plane are represented by the followingexpressions (d) and (e):

ΔM′={meridional value (y′=0.7field, z=0, θ=0.7°)−meridional value(y′=−0.7field, z=0, θ=0.7°)}/2  (d)

ΔS′={sagittal value(y′=0.7field, z=0, θ=0.7°)−sagittalvalue(y′=−0.7field, z=0, θ=0.7°)}/2  (e)

[Axial Coma] (FIG. 1C)

In FIG. 1C, 7 is an axial luminous flux and 8 is an axial principal ray.Since the axial luminous flux 7 is not symmetrical with respect to theaxial principal ray 8 as shown in the figure, coma is caused. Axial comaAXCM caused in the axial luminous flux 7 is represented by the followingexpression (f):

AXCM={Y(Upper Zonal, θ=0.7°)+Y(Lower Zonal, θ=0.7°)}/2  (f)

[Axial Lateral Chromatic Aberration] (FIG. 1D)

The image point shifts due to the difference in wavelength. Therefore,when the optical system is asymmetrical, the image point shifts also inthe axial light. Axial lateral chromatic aberration caused in the axialprincipal ray is represented by the following expression (g):

(Axial lateral chromatic aberration)={Y(g-line, θ=0.7°)−Y(d-line,θ=0.7°)}  (g)

With respect to the above-described decentering aberrations, YoshiyaMatsui's paper “Third-order Aberration Theory of Optical System WhereDecentering Exits” (JOEM, June 1990) shows an application method.Although the method is suitable for a case where the normal taking lenssystem is decentered due to an attachment error, it cannot be directlyapplied to the image blur compensating optical system where the coaxialrelationship among the object plane, the taking lens system and theimage plane breaks. In order that the method of the paper may bedirectly applied to the image blur compensating optical system, theaberrations of the actual image blur compensating optical system areexpressed by normal third-order aberration coefficients by performingthe following conversions of expressions:

[Application of Decentering Aberration Coefficients to Image blurcompensating Optical System]

Referring to FIGS. 2A and 2B showing the relationship between theoptical system and the coordinates, how to obtain decentering aberrationcoefficients will be described. In FIG. 2A, ax is a reference axis ofthe optical system, PS1 is an entrance pupil surface, PS2 is an exitpupil surface, and HS1 and HS2 are principal planes. FIGS. 2B shows theportion of PT in FIG. 2A. First, the expressions are defined as follows:

tan ω·cos φω=y/g$

tan ω·sin φω=Z/g$

R·cos φR=(g$/g)·Y*

R·sin φR=(g$/g)·Z*

where g is the distance from the entrance pupil surface to the objectplane (object surface) OS, g$ is the distance from the object sideprincipal plane to the object plane OS, ω is an angle which the straightline between the object point and the object side principal point Hforms to the reference axis, φω is its azimuth, R is the entrance pupilradius converted onto the object side principal plane, and φR is itsazimuth.

The image point shift amounts ΔY and ΔZ on the image plane (imagesurface) IS when a νth surface counted from the object side is paralleldecentered in the direction of the Y-axis by a small amount Eν arerepresented by the following expressions (1A) and (1B):

ΔY=−(Eν/2α_(k)′)·[(ΔE)ν+(N·tan ω)²·{(2+cos 2φω)·(VE1)ν−(VE2)ν}

+2R·(N·tan ω)·{(2 cos(φR−φω)+cos(φR+φω))·(IIIE)ν+cos φR·cosφω·(PE)ν}+R²·(2+cos 2φR)·(IIE)ν]  (1A)

ΔZ=−(Eν/2α_(k)′)·[(N·tan ω)²·sin 2φω·(VE1)ν+2R·(N·tan ω)

·{sin(φR+φω)·(IIIE)ν+sin φR·sin φω·(PE)ν}+R²·sin 2φR·(IIE)ν]  (1B)

Here, when (ΔE)ν is a prismatic effect (lateral shift of the image),(VE1)ν and (VE2)ν are rotationally asymmetric distortions, (IIIE)ν and(PE)ν are a rotationally asymmetric astigmatism and an inclination ofthe image surface, respectively, and (IIE)ν is a rotationally asymmetriccoma which is present also on the axis, the decentering aberrationcoefficients representing the effects of the decentering are representedby the following expressions (1C) to (1H) based on the aberrationcoefficients of from the νth surface to the image surface (# is a suffixrepresentative of “on the object surface”). In the case of rotationaldecentering, the decentering aberration coefficients are represented byexpressions similar to the expressions (1A) to (1H):

(ΔE)ν=−2(αν′−αν)  (1C)

(VE1)ν=[{αν′·(μ=ν+1→k)ΣVμ)−{αν·(μ=ν→k)ΣVμ}]−[{αν′#·(μ=ν+1→k)ΣIIIμ}−{αν#·(μ=ν→k)ΣIIIμ}]  (1D)

(VE2)ν={αν′#·(μ=ν+1→k)ΣPμ}−{αν#·(μ=ν→k)ΣPμ}  (1E)

(IIIE)ν=[{αν′·(μ=ν+1→k)ΣIIIμ}−{αν·(μ=ν→k)ΣIIIμ}]−[{αν′#·(μ=ν+1→k)ΣIIμ}−{αν#·(μ=ν→k)ΣIIμ}]  (1F)

(PE)ν={αν′·(μ=ν+1→k)ΣPμ}−{αν·(μ=ν→k)ΣPμ}  (1G)

(IIE)ν=[{αν′·(μ=ν+1→k)ΣIIμ}−{αν·(μ=ν→k)ΣIIμ}]−[{αν′#·(μ=ν+1→k)ΣIμ}−{αν#·(μ=ν→k)ΣIμ}]  (1H)

However, in order to apply the decentering aberration coefficients tothe image blur compensating optical system, it is necessary to use theaberration coefficients from the image surface IS by reversing theoptical system to replace the image surface IS with the object surfaceOS. That is, the image point shift amount must be converted to that onthe object surface OS. The reasons therefor will be described below.

The first reason is that the light passage position varies due todecentering. As shown in FIG. 3A (L₁ is a light ray before decenteringand L₂ is a light ray after decentering), according to the method shownin the above-mentioned paper of Yoshiya Matsui's, the light passageposition on the image surface IS side of a decentered lens LS is changedby the decentered lens LS. Consequently, the aberration coefficients ofthe decentered lens LS and the lens units disposed between thedecentered lens LS and the image surface IS relate to the decenteringaberration coefficients. On the contrary, as shown in FIG. 3B (M₁ is alight ray before image blur compensation and M₂ is a light ray afterimage blur compensation), in the image blur compensating optical system,(ideally,) the light passage position on the object side of thedecentered lens LS before the image blur compensation is different fromthat after image blur compensation. Consequently, the aberrationcoefficients of the decentered lens LS and the lens units disposed onthe object side thereof relate to the decentering aberrationcoefficients.

The second reason is that aberration degradation is caused due to therotational conversion of the object surface. According to the method ofthe above-described paper of Yoshiya Matsui's, an object surface OS₁ andthe image surface IS are both immovable. In the image blur compensatingoptical system, however, the object surface OS₁ rotates as shown in FIG.4. For this reason, the off-axial image point shift error and theone-side blur largely differ from those in the case where the objectsurface OS₁ does not rotate. In FIG. 4, OS₁ is the object surface beforethe image blur compensation and OS₂ is the object surface after theimage blur compensation.

[Aberration Coefficients of Reversed Optical System and AberrationCoefficients of Non-reversed Optical System]

Since the image point shift amount must be converted to that on theobject surface for the reasons described above, the coefficients of theexpressions (1A) to (1H) are converted according to the expressions (2A)to (2J) shown below represented based on FIG. 5 (non-reversed opticalsystem). In FIG. 5, PS is the pupil surface, HS is the principal plane,S1 is the front surface of the optical system, and S2 is the rearsurface of the optical system. ^(R)( ) is a symbol of the reversedoptical system and N is a refractive index.

^(R)α=^(R)N/^(R)g$=−α′  (2A)

^(R)α#=α′#  (2B)

^(R)αμ′=−αν  (2C)

^(R)αμ′#=αν#  (2D)

^(R)Pμ=Pν  (2E) . . . same

^(R)φμ=φν  (2F) . . . same

^(R)Iμ=Iν  (2G) . . . same

^(R)IIμ=−IIν  (2H) . . . reverse

^(R)IIIμ=IIIν  (2I) . . . same

^(R)Vμ=−Vν  (2J) . . . reverse

[Decentering aberration coefficients and image blur aberrationcoefficients when compensating lens unit parallely decenters]

Since the previously-mentioned expressions (1A) to (1H) show a casewhere only one surface V is decentered, they are converted toexpressions showing a case where a plurality of surfaces i to j aredecentered. When the compensating lens unit is parallely decentered,since the decentering amounts Ei to Ej of the decentered surfaces i to jare the same, the aberration coefficients can be treated as a sum asshown in the following expression:

(ΔE)i to j=(ν=i→j)Σ{−2·(αν′−αν)}

From αν′=αν+1, the following expression is obtained:

(ΔE)i to j=−2·(αj′−αi)

Likewise, with respect to other aberration coefficients, the termsbetween Σs are deleted. For example,

(PE)i toj=(μ=i→j)Σ{αν′·(μ=ν+1→k)ΣPμ−αν·(μ=ν→k)ΣPμ}=αj′·(μ=j+1→k)ΣPμ−αi·(μ=i→k)ΣPμ

This is further converted to

(PE)i to j=(αj′−αi)·(μ=j+1→k)ΣPμ−αi·(μ=i→j)ΣPμ

where (μ=j+1→k)ΣPμ is the sum of P (Petzval) of the lenses arrangedbehind the compensating lens unit, and (μ=i→j)ΣPμ is the sum of P of thecompensating lens unit.

(PE)i to j=(αj′−αi)P_(R)−αi·P_(D)

where ( )_(R) is the sum of the aberration coefficients of the lensesarranged behind the compensating lens and ( )_(D) is the sum of theaberration coefficients of the compensating lens unit.

As described above, by the conversion of the image point movementamounts to those of the object surface and the conversion of theexpressions to the expressions showing the case where a plurality ofsurfaces i to j are decentered, the decentering aberration coefficientsrepresented by the following expressions (3A) to (3F) are obtained. Byre-defining the decentering aberration coefficients according to theexpressions (3A) to (3F), the expressions (1A) to (1H) can be used asthey are as expressions representing the image point movement amounts onthe object surface.

(ΔE)i to j=−2·(αj′−αi)  (3A)

(VE1)i toj=(αj′−αi)·V_(R)−(αj′#−αi#)·III_(R)−(αi·V_(D)−αi#·III_(D))  (3B)

(VE2)i to j=(αj#−αi#)·P_(R)−αi#·P_(D)  (3C)

(IIIE)i toj=(αj′−αi)·III_(R)−(αj′#−αi#)·II_(R)−(αi·III_(D)−αi#·II_(D))  (3D)

(PE)i to j=(αj′−αi)·P_(R)−αi·P_(D)  (3E)

(IIE)i to j=(αj′−αi)·II_(R)−(αj′#−αi#)·I_(R)−(αi·II_(D)−αi#·I_(D))  (3F)

[Off-axial image point movement error]

Subsequently, the off-axial image point movement error will bedescribed. The decentering aberration coefficients (of the reversaloptical systems) are represented by ΔE, VE1, VE2, IIIE, PE and IIE. Themovements of the image point (before rotational conversion on the objectsurface) due to decentering on the object surface are represented by thefollowing expressions (4A) and (4B) (in the principal light beam (R=0)).The expressions (4A) and (4B) are the expressions (1A) and (1B) whereR=0.

ΔY#=−(E/2α′_(k))·[ΔE+(N·tan ω)²·{(2+cos²φω)VE1−VE2}]  (4A)

ΔZ#=−(E/2α′)·{(N·tan ω)²·sin 2φω)·VE1}  (4B)

Based on the expressions (4A) and (4B), the following expressions (4C)and (4D) are obtained (axial light beam, tan ω=0):

 ΔY₀#=−(E/2α′_(k))·ΔE  (4C)

ΔZ₀#=0  (4D)

Subsequently, the rotational conversion will be described with referenceto FIGS. 6A and 6B. From FIG. 6A, the following expression holds:

Y#=g$_(k)·tan ω

From the sine theorem,

Y′#/{sin(π/2−ω′)}=(Y#+ΔY#−ΔY₀#)/{sin(π/2+ω′−θ)}

ΔY′# after the rotational conversion is represented by the followingexpression:

ΔY′#=(Y′#)−(Y#)

 =[Y#·cos ω′+{(ΔY#)−(ΔY₀#)}·cos ω′−Y#·cos(ω′−θ)]/cos(ω′−θ)

Only the numerators of this expression are converted.

[Y#·cos ω′+{(ΔY#)−(ΔY₀#)}·cos ω′−Y#·cos(ω′θ)]=Y#·cosω′+{(ΔY#)−(ΔY₀#)}·cos ω′−Y#·cos θ·cos ω′−Y#·sin θ·sinω′

 =(1−cos θ)·Y#·cos ω′+{(ΔY#)−(ΔY₀#)}cos ω′−Y#·sin θ·sin ω′

Here, since θ is small and ignorable compared to the other values,(1−cos θ)≈θ²/2, sin θ≈θ, and cos ω′/{cos(ω′−θ))≈1, sinω′/{cos(ω′−θ)}≈tan ω.

Therefore, the following expression is obtained:

ΔY′#≈(ΔY#−ΔY₀#)−Y#·θ·tan ω

(ΔY#−ΔY₀#) represents the off-axial image point movement error ofparallel decentering and Y#·θ·tan ω is an additional term (irrelevant tothe aberration coefficients) due to rotation. Since ω at this time is onan X-Y cross section,

ΔY′#≈(ΔY#−ΔY₀#)−Y#·θ·tan ω·cos φω  (5A)

Subsequently, the conversion to the image surface IS will be describedwith reference to FIG. 7. A magnification β is represented by thefollowing expression:

β=g$₁/g$_(k)=α_(k)′/α₁

where α₁=1/g$₁. The relationship between the image surface IS and theobject surface OS is represented by the following expression:

Y=β·Y#

Y# and ΔY# which take the form of 1/a_(k)′×( ) are converted as follows:

Y=β·Y#

 =(α_(k)′/α₁)·(1/α_(k)′)×( )

 =g$₁×( )

Here, if g$_(k)→∞, g$₁=−F1. Therefore, the following expression holds:

Y=−Fl×( )

 =−Fl×α_(k)′×Y_(#)

Subsequently, the off-axial image point movement error on the imagesurface will be described. From the expression (4C) andα_(k)′=1/g_(k)′$, a decentering amount E is represented by the followingexpressions:

θ=ΔY₀#/g$_(k)′=E·ΔE/2

E=2·θ/ΔE

Normalization is performed so that the image blur compensation angle θis constant (0.7 deg=0.0122173 rad).

By performing parallel decentering (rotational decentering is notperformed) to image-surface-convert ΔY=(ΔY#−ΔY₀#) (here, N·tan ω=Φ/Fl,Φ²=Y²+Z²), the following expressions (6A) to (6D) are obtained:

ΔY=(θ·Φ²/Fl)·[{(2+cos 2·φω)·VE1−VE2}/ΔE]  (6A)

ΔZ=(θ·Φ²/Fl)·[{(sin 2·φω)·VE1−VE2}/ΔE]  (6B)

Y₊ Image Point, Y⁻ Image Point {φω=0, π of expressions (6A) and (6B)}:

ΔY_(Y)=(θ·Y²/Fl)·{(3·VE1−VE2)/ΔE}  (6C)

Z Image Point{φω=π/2 of expressions (6A) and (6B)}:

ΔY_(Z)=(θ·Z/Fl)·{(VE1−VE2)/ΔE}  (6D)

Then, rotational conversion is performed. Since Y#=−Y/(Fl×a_(k)′), withrespect to −Y#·θ·tan ω·cos φω of the expression (5A), the followingexpression holds:

−Y#·θ·tan ω·cos φω=Y/(Fl×α_(k)′)·θ·tan ω·cos φω

At the Y₊ image point and the Y⁻ image Point, since φω=0, π and tanω/a_(k)′=Y, −Y#·θ·tan ω·cos φω on the image surface is −Y#·θ·tan ω·cosφω=Y²·θ/Fl. By adding this to the expression (6C), the followingexpression (6E) is obtained. At the Z image point, since φω=π2,−Y#·θ·tan ω·cos φω on the image surface is −Y#·θ·tan ω·cos φω=0. Byadding this to the expression (6D), the following expression (6F) isobtained:

ΔY_(Y)′=(θ·Y²/Fl)·{(3·VE1−VE2−ΔE)/ΔE}  (6E)

ΔY_(Z)′=ΔY_(z)  (6F)

[One-side blur]

Subsequently, the one-side blur will be described. From the expressions(1A) and (1B), ΔM is {(primary term of R) of ΔY φR=0}×g$_(k)′ and ΔS is{(primary term of R) of ΔZ φR=π/2}×g$_(k)′. Before rotation, thefollowing expression holds on the object surface OS (here,a_(k)′=N_(k)′/g$_(k)′ and E/2=θ/ΔE are used):

ΔM#=(−g$_(k)′²·θ/N_(k)′)×2·R·(N·tan ω)·cos φω·{(3·IIIE+PE)/ΔE}

After the rotation, the following expression holds:

ΔM′#≈ΔM#+θY#

By converting the aberration coefficients to those on the image surfaceand substituting N_(k)′=1 and N=1, the following expression is obtained:

ΔM′=β²·ΔM′#

 =−g$²·θ×2·R·tan ω·cos φω·{(3·IIIE+PE)/ΔE}+β·Y·θ

If the object surface OS is ∞ (here, g$₁=−F1, β→0, tan ω=Y/F1 and φω=0),the following expression (7A) representative of a meridional one-sideblur ΔM′ is obtained. Likewise, an expression (7B) representative of asagittal one-side blur is obtained.

ΔM′=−2·Fl·Y·θ·R·{(3·IIIE+PE)/ΔE}  (7A)

ΔS′=−2·Fl·Y·θ·R·{(IIIE+PE)/ΔE}  (7B)

[Axial coma]

Subsequently, axial coma will be described. Based on the expression(1A), coma by ω=0 and upper decentering is represented by the followingexpression:

ΔY_(Upper)#=ΔY#(ω=0, φ_(R)=0) ΔY#(ω=0, R=0)=−E/(2·α′)×R²×3·IIE

Coma by ω=0 and lower decentering (the same as ΔY_(upper)# including thesign) is represented by the following expression:

ΔY_(Lower)#=ΔY#(ω=0, φ_(R)=π)ΔY#(ω=0, R=0)=−E/(2·α′)×R²×3·IIE

Since ω=0, axial coma is hardly varied by the rotational conversion. Bythe conversion from the object surface OS to the image surface IS(ΔY=β·ΔY#, E/2=θ/ΔE), the following expression is obtained

 ΔY_(Upper)=Fl×θ×R²×(3·IIE/ΔE)=ΔY_(Lower)

The axial coma AXCM is represented by the following expression (8A):

AXCM=(ΔY_(Upper)+ΔY_(Lower))/2

 =ΔY_(Upper)  (8A)

A part of each of the expressions (6E), (6F), (7A), (7B) and (8A) isnewly defined as an aberration coefficient represented by the followingexpressions (9A) to (9E):

Off-axial image-point movement error of an image point on the Y axis:

VE_(Y)={(3·VE1−VE2−ΔE)/ΔE}  (9A)

Off-axial image-point movement error of an image point on the Z axis:

VE_(Z)={(VE1−VE2)/ΔE}  (9B)

Meridional single-sided blur:

IIIE_(M)={(3·IIIE+PE)/ΔE}  (9C)

Sagittal single-sided blur:

IIIE_(S)={(IIIE+PE)/ΔE}  (9D)

Off-axial coma:

IIE_(A)={(3·IIE)/ΔE}  (9E)

By substituting the expressions (3A) to (3F) in the expressions (9A) to(9B) representative of the image blur aberration coefficients, thefollowing expressions (10A) to (10E) representative of image bluraberration coefficients are obtained:

VE_(Y)=−½·{3V_(R)−3V_(D)·A+2−(3·III_(R)+P_(R))·H#+(3·III_(D)+P_(D))·A#}  (10A)

VE_(Z)=−½·{V_(R)−V_(D)·A−(III_(R)+P_(R))·H#+(III_(D)+P_(D))·A#}  (10B)

 IIIE_(M)=−½·{(3·III_(R)+P_(R))−(3·III_(D)+P_(D))·A−3·II_(R)·H#+3·II_(D)·A#}  (10C)

IIIE_(S)=−½·{(III_(R)+P_(R))−(III_(D)+P_(D))·A−II_(R)·H#+II_(D)·A#}  (10D)

IIE_(A)=−{fraction (3/2)}·(II_(R)+II_(D)·A−I_(R)·H#+I_(D)·A#)  (10E)

where ( )_(D) is the sum of the aberration coefficients of thecompensating lens unit;

( )_(R) is the sum of the aberration coefficients of the lens unitsarranged behind (on the object side of) the compensating lens unit;

A=αi/(αj′−αi) (here, the compensating lens units are i to j);

A#=αi#/(αj′−αi); and

H#=(αi′#−αi#)/(αj′−αi).

ΔE=−2·(αj′−αi) (here, (αj′−αi) is ±0.0122173 when 0.7°/mm) which is thecoefficient of (image blur compensation angle)/(decentering amount) aimssubstantially at a predetermined value (however, the sign differsaccording to whether the compensating lens units are positive ornegative). Therefore, A is an incident angle of a marginal light beam tothe compensating lens units (viewed from the image side) and A# isproportional to the incident angle of the principal light beam. When h#and h do not vary so much in the compensating lens units, H# representsa ratio between h# of the principal light beam and h of the marginallight beam.

Since the decentering aberration coefficients in the expressions (10A)to (10E) are defined as those of the reversal optical system, it isnecessary to return them to the coefficients of the non-reversal opticalsystem. Returning the coefficients in the expressions (10A) to (10E) byusing the expressions (2A) to (2J), the following expressions (11A) to(11E) are obtained:

VE_(Y)=+½·{3V_(F)−3V_(D)·A−2+(3·III_(F)+P_(F))H#−(3·III_(D)+P_(D))·A#}  (11A)

VE_(Z)=+½·{V_(F)−V_(D)·A+(III_(F)+P_(F))H#−(III_(D)+P_(D))·A#}  (11B)

IIIE_(M)=−½·{(3·III_(F)+P_(F))−(3·III_(D)+P_(D))·A+3·II_(F)·H#−3·II_(D)·A#}  (11C)

IIIE_(S)=−½·{(III_(F)+P_(F))−(III_(D)+P_(D))·A+II_(F)·H#−II_(D)·A#}  (11D)

IIE_(A)=+{fraction (3/2)}·(II_(F)−II_(D)·A+I_(F)·H#−I_(D)·A_(#))  (11E)

where ( )_(D) is the sum of the aberration coefficients of thecompensating lens units and the reversal optical system;

( )_(F) is the sum of the aberration coefficients of the lens unitsarranged in front of the compensating lens units;

A=−αn′/(αn′−αm);

A#=αn′#/(αn′−αm);

H=−(αn′#−αm#)/(αn′−αm)=−(Σhμ#·φμ)/(Σhμ·φμ); and

ΔE=−2(αn′−αm) (compensating lens units: m→n, non-reversal lens system:j←i).

The following are understood from the expressions (11A) to (11E): First,while according to the method of the abovementioned paper of YoshiyaMatsui's, the image blur compensating lens unit (i.e. the decenteredlens LS) and succeeding lens units relate to the optical quality asdescribed previously, according to the expressions (11A) to (11E), theimage blur compensating lens unit and the preceding lens units arerelated to the optical performance. Second, the off-axial image pointshift error tends to increase in wide-angle lens systems (the focallength Fl of the image blur compensating lens unit is the denominator)and the one-side blur and the axial coma tend to increase in telephotolens systems.

Third, while the aberration degradation at the time of decentering isreduced by decreasing the aberration coefficients of the image blurcompensating lens unit and the preceding lens units, a constant (−2 in {} of the expression (11A)) is left in the coefficient VE_(Y) of theoff-axial image point shift error ΔY_(Y)′. This is a term which occursbecause of an inclined relationship between the object surface OS andthe image surface IS due to deflection in the rotation. The off-axialimage point shift error due to the constant term (−2) is great inwide-angle lens systems. For example, when the focal length Fl is 38 mm,the off-axial image point shift error ΔY_(Y)′ is −72 μm, which cannot beignored. Moreover, the off-axial image point shift error due to theconstant term (−2) is left even if the aberration coefficients are “0”.Therefore, it is desirable to set the aberration coefficients so thatthe constant term (−2) is canceled.

Fourth, in order to reduce the aberration degradation at the time ofdecentering, it is necessary to reduce the aberration coefficients andthe coefficients such as A, A# and H# multiplied by the aberrationcoefficients. In order to reduce A and A#, the denominator α_(n)′−α_(m)is increased. Since this is directly related to ΔE=−2(α_(n)′−α_(m)′), ifthe denominator is increased too much, the blur compensation sensitivity(how many degrees the luminous flux is bent at when the lens isdecentered by certain millimeters) becomes too high, so that mechanicaldriving accuracy is necessary. With respect to H#, the closer the imageblur compensating lens unit is to the aperture diaphragm, the smaller h#of each surface is and the smaller H# is.

<First to Fourth Embodiments>

Zoom lens systems having an image blur compensating function accordingto the first to fourth embodiments will be described with reference tothe drawings. FIGS. 8, 12, 16 and 20 show the lens arrangements of thefirst to fourth embodiments in the normal condition (pre-decenteringcondition) at the wide-angle limit [W]. In the figures, the surfacemarked with ri (i=1, 2, 3, . . . ) is an ith surface counted from theobject side, and the axial distance marked with di (i=1, 2, 3, . . . )is an ith axial distance counted from the object side. Arrows m1, m2,m3, m4 and m5 of FIGS. 8, 12, 16 and 20 schematically show zoommovements of a first lens unit Gr1, a second lens unit Gr2, a third lensunit Gr3, an aperture diaphragm S and a fourth lens unit Gr4, and afifth lens unit Gr5 from the wide-angle limit [W] to the telephoto limit[T].

A zoom lens system of the first embodiment consists of, from the objectside, a first lens unit Gr1 having a positive refractive power, a secondlens unit Gr2 having a negative refractive power, a third lens unit Gr3having a negative refractive power, a fourth lens unit Gr4 having apositive refractive power, and a fifth lens unit Gr5 having a negativerefractive power, wherein zooming is performed by varying the distancesbetween the lens units. Image blur compensation is made by paralleldecentering the second lens unit Gr2, that is, by moving it vertically(i.e. in a direction perpendicular) to the optical axis AX. In FIG. 8,arrow C represents the movement of the second lens unit Gr2 during imageblur correction.

Zoom lens systems of the second to fourth embodiments consist of, fromthe object side, a first lens unit Gr1 having a positive refractivepower, a second lens unit Gr2 having a negative refractive power, athird lens unit Gr3 having a positive refractive power, a fourth lensunit Gr4 having a positive refractive power, and a fifth lens unit Gr5having a negative refractive power, wherein zooming is performed byvarying the distances between the lens units. Image blur compensation ismade by parallel decentering the second lens unit Gr2. In FIGS. 12, 16,and 20, arrow C represents the movement of the second lens unit Gr2during image blur correction.

The first to fourth embodiments include from the object side the firstlens unit Gr1 having a positive refractive power and the second lensunit Gr2 having a negative refractive power, and include on the mostimage side the last lens unit (i.e. the most image side lens unit)having a negative refractive power. In this type of zoom lens systems,since the degree of freedom of the movements of the zoom lens units areeffectively used for aberration correction, excellent image quality isobtained in the entire zoom range.

Since the first lens unit Gr1 and the fifth lens unit Gr5 which is thelast lens unit are moved toward the object side during zooming from thewide-angle limit [W] to the telephoto limit [T], a telephoto zoom lenssystem is achieved which is compact but has a sufficient back focallength. Since the last lens unit has a negative refractive power, asufficient back focal length and compactness are simultaneouslyachieved. Further, by arranging so that the second lens unit Gr2 and thethird lens unit Gr3 are moved during zooming from the wide-angle limit[W] to the telephoto limit [T], the degree of freedom of the movementsof the zoom lens units increases, so that an optical system is obtainedwhich is advantageous in correcting aberration and has a further reducedtotal length.

The first to fourth embodiments fulfill the conditions (1) and (2) shownbelow. Since the first to fourth embodiments are five-unit zoom lenssystems, the following conditions (1a) and (2) are fulfilled:

0.2<|fL/fW|<0.4  (1)

0.2<|f5/fW|<0.4  (1a)

0.2<|f2/fW|<4.0  (2)

where fL is the focal length of the last lens unit, fW is the focallength of the entire lens system at the wide-angle limit [W], f2 is thefocal length of the second lens unit Gr2, and f5 is the focal length ofthe fifth lens unit Gr5.

The conditions (1) and (1a) define the length of the focal length of thelast lens unit. When the upper limit of the conditions (1) and (1a) isexceeded, the refractive power of the last lens unit is weakened and theproportion of its contribution to zooming decreases, so that the zoommovement amount increases. If the zoom movement amount increases, thetotal length increases, so that compactness is lost. When the conditions(1) and (1a) are fulfilled with an upper limit of 0.38, a more compactzoom optical system is obtained. When the lower limit of the conditions(1) and (1a) is exceeded, the refractive power of the last lens unit istoo strong, so that an enormous amount of aberration is caused and it isdifficult to restrain the aberration by use of another lens unit. Whenthe conditions (1) and (1a) are fulfilled with a lower limit of 0.27, azoom optical system which is more excellent in image quality isobtained.

In zoom taking optical systems for single lens reflex cameras, it istypical that the first lens unit Gr1 is the largest lens unit and isconsiderably heavy in weight. Therefore, in zoom lens systems like thefirst to fourth embodiments including from the object side the firstlens unit Gr1 having a positive refractive power and the second lensunit Gr2 having a negative refractive power and including on the mostimage side the last lens unit having a negative refractive power whereinzooming is performed by varying the distances between the lens units andthe first lens unit Gr1 and the last lens unit are moved toward theobject side during zooming from the wide-angle limit [W] to thetelephoto limit [T], the first lens unit Gr1 is heavy in weight comparedwith the second lens unit Gr2 and succeeding lens units. For thisreason, it is undesirable to make image blur compensation by moving thefirst lens unit Gr1 vertically to the optical axis AX (i.e. by paralleldecentering it) because this requires for the image blur compensationdriving system to increase in size.

For this reason, in the first to fourth embodiments, image blurcompensation is made by moving the second lens unit Gr2 vertically tothe optical axis AX. Since the second lens unit Gr2 is small in diameterand light in weight compared with the first lens unit Gr1, by using thesecond lens unit Gr2 for image blur compensation, image blur iscompensated without any increase in burden on the image blurcompensation driving system. Moreover, the second lens unit Gr2 has acharacteristic that its movement amount during zooming from thewide-angle limit [W] to the telephoto limit [T] is small compared withthe other lens units. This characteristic is advantageous in makingimage blur compensation, and also in that regard, the second lens unitGr2 is superior as the image blur compensating lens unit. In the fourthembodiment, the second lens unit Gr2 is stationary during zooming. Thearrangement where the second lens unit Gr2 serving as the image blurcompensating lens unit is stationary during zooming is desirable becauseit is advantageous in disposing the image blur compensation drivingsystem in the lens barrel.

The condition (2) defines the length of the focal length of the secondlens unit Gr2. When the upper limit of the condition (2) is exceeded,the refractive power of the second lens unit Gr2 is too weak, so thatthe sensitivity for the movement of the second lens unit Gr2 vertical tothe optical axis AX to move the image point is too weak. For thisreason, the movement amount of the second lens unit Gr2 at the time ofimage blur compensation increases. When the condition (2) is fulfilledwith an upper limit of 2.0, the movement amount of the second lens unitGr2 at the time of image blur compensation is further reduced. When thelower limit of the condition (2) is exceeded, the refractive power ofthe second lens unit Gr2 is too strong, so that the amount of aberrationcaused in the normal condition and the amount of aberration caused inthe compensated condition at the time of image blur both increase and itis difficult to restrain the aberration by use of another lens unit.When the condition (2) is fulfilled with a lower limit of 0.3, moreexcellent image quality is obtained.

The first to fourth embodiments further fulfill the following condition(3):

f1/fW<1.10  (3)

where f1 is the focal length of the first lens unit Gr1.

The condition (3) defines the length of the focal length of the firstlens unit Gr1. When the upper limit of the condition (3) is exceeded,the refractive power of the first lens unit Gr1 is weakened, so that themovement amount during zooming increases. Since the total length and thelens diameter increase for this reason, compactness is lost. When thecondition (3) is fulfilled with an upper limit of 1.00, a more compactzoom optical system is obtained.

When a lens unit is moved vertically to the optical axis AX for imageblur compensation, in the compensated condition (post-decenteringcondition), the light passes through a place where no light passes inthe normal condition (pre-decentering condition). There is a possibilitythat the light becomes harmful light and degrades the image quality.Therefore, it is desirable to cut off the harmful light during imageblur compensation by providing a stationary aperture diaphragm S on theobject side of the second lens unit Gr2 serving as the image blurcompensating lens unit, in the second lens unit Gr2 or on the image sideof the second lens unit Gr2. By doing so, excellent image quality isobtained in the image blur compensated condition.

It is desirable to perform focusing to a near object by use of thesecond lens unit Gr2 serving as the image blur compensating lens unit.By doing so, the driving system for focusing and the driving system forimage blur compensation may be realized by use of a common drivingmember. This is advantageous in view of the cost.

It is desirable that the movement amount of the image blur compensatinglens unit (in this case, the second lens unit Gr2) at the time of imageblur (this movement amount will hereinafter be referred to as “imageblur compensation movement amount’) at the wide-angle limit [W] and thatat the telephoto limit [T] do not largely differ from each other.Therefore, the first to fourth embodiments further fulfill the followingcondition (4):

0.4<MT/MW<2.5  (4)

where MT is the blur compensation movement amount of the second lensunit Gr2 at the telephoto limit [T] and MW is the blur compensationmovement amount of the second lens unit Gr2 at the wide-angle limit [W].

When the upper limit or the lower limit of the condition (4) isexceeded, the image blur compensation movement amount at the wide-anglelimit [W] and that at the telephoto limit [T] largely differ from eachother, so that error is prone to be caused in calculating the image blurcompensation amount at a given focal length.

When the image blur compensating lens unit is parallel decentered at thetime of image blur, axial lateral chromatic aberration which is one ofthe decentering aberrations is caused. To restrain this, it is desirablethat the second lens unit Gr2 serving as the image blur compensatinglens unit be color-corrected. Therefore, the first to fourth embodimentsfulfill the following condition (5):

νp>νn  (5)

where νp is the Abbe number of a positive lens element included in thesecond lens unit Gr2 and νn is the Abbe number of a negative lenselement included in the second lens unit Gr2.

The arrangements of the first to fourth embodiments (FIGS. 8, 12, 16 and20) will be specifically described with reference to their constructiondata and aberration qualities. Tables 1 to 4 show construction data ofthe first to fourth embodiments. In the tables, ri (i=1, 2, 3, . . . )is the radius of curvature of an ith surface counted from the objectside, di (i=1, 2, 3, . . . ) is an ith axial distance counted from theobject side (in these tables, axial distances before decentering areshown), Ni (i=1, 2, 3, . . . ) and νi (i=1, 2, 3, . . . ) are therefractive index (Nd) and the Abbe number (νd) to the d-line of an ithlens counted from the object side. The axial distances varied duringzooming are actual axial distances between the lens units at thewide-angle limit [W], at the middle focal length condition [M] and atthe telephoto limit [T]. Tables 1 to 4 also show the focal length f andthe F-number FNO of the entire lens system corresponding to theconditions [W], [M] and [T]. Note that the definitions and the likegiven above in connection with Tables 1 to 4 apply also to Tables 7 to10, 12 to 17, 20 to 23, and 25 to 27, which will be described later.Table 5 shows values of the conditions (1) to (4) in the first to fourthembodiments.

FIGS. 9A to 9I, 13A to 13I, 17A to 17I and 21A to 21I show longitudinalaberration curves of the first to fourth embodiments. FIGS. 9A to 9C,13A to 13C, 17A to 17C and 21A to 21C show aberration curves at thewide-angle limit [W] in the normal condition (pre-decenteringcondition). FIGS. 9D to 9F, 13D to 13F, 17D to 17F and 21D to 21F showaberration curves at the middle focal length condition [M] in the normalcondition. FIGS. 9G to 9I, 13G to 13I, 17G to 17I and 21G to 21I showaberration curves at the telephoto limit [T] in the normal condition.

FIGS. 9A, 9D, 9G, 13A, 13D, 13G, 17A, 17D, 17G, 21A, 21D and 21G showspherical aberration and sine condition. The solid line d representsaberration to the d-line. The broken line SC represents sine condition.FIGS. 9B, 9E, 9H, 13B, 13E, 13H, 17B, 17E, 17H, 21B, 21E and 21H showastigmatism. The broken line DM and the solid line DS representastigmatisms on the meridional image plane and on the sagittal imageplane, respectively. FIGS. 9C, 9F, 9I, 13C, 13F, 13I, 17C, 17F, 17I,21C, 21G and 21I show distortion.

FIGS. 10A to 10E, 14A to 14E, 18A to 18E and 22A to 22E show lateralaberration curves of the first to fourth embodiments at the wide-anglelimit [W]. FIGS. 11A to 11E, 15A to 15E, 19A to 19E and 23A to 23E showlateral aberration curves of the first to fourth embodiments at thetelephoto limit [T].

FIGS. 10A, 10B, 11A, 11B, 14A, 14B, 15A, 15B, 18A, 18B, 19A, 19B, 22A,22B, 23A and 23B show lateral aberration (image height Y′=12, 0) withrespect to the luminous flux on the meridional image plane before thedecentering of the second lens unit Gr2 in the first to fourthembodiments. FIGS. 10C to 10E, 11C to 11E, 14C to 14E, 15C to 15E, 18Eto 18E, 19C to 19E, 22C to 22E and 23C to 23E show lateral aberration(image height Y′=−12, 12, 0) with respect to the luminous flux on themeridional image plane after the decentering of the second lens unit Gr2in the first to fourth embodiments. The aberration curves after thedecentering show aberrations in the compensated condition when an imageblur compensation angle θ of the second lens unit Gr2 is 0.7°(=0.0122173 rad.).

As described above, in the first to fourth embodiments, since the secondlens unit Gr2 being small in diameter and light in weight is used forimage blur compensation, the burden on the image blur compensating lensunit is lightened. In addition, the zoom movements and powerarrangements of the lens units and the fulfillment of theabove-described conditions reduce the total length to achievecompactness and are effective in obtaining excellent image quality byexcellently correcting aberrations in both the normal and compensatedconditions. The fourth embodiment where the second lens unit Gr2 servingas the image blur compensating lens unit is stationary during zooming isadvantageous in arranging the image blur compensation driving system inthe lens barrel.

<Fifth to Ninth Embodiments>

Zoom lens systems having an image blur compensating function accordingto the fifth to ninth embodiments will be described with reference tothe drawings. FIGS. 24, 28, 32, 36 and 40 show the lens arrangements ofthe fifth to ninth embodiments in the normal condition (pre-decenteringcondition) at the wide-angle limit [W]. In the figures, the surfacemarked with ri (i=1, 2, 3, . . . ) is an ith surface counted from theobject side, and the axial distance marked with di (i=1, 2, 3, . . . )is an ith axial distance counted from the object side. Arrows m1, m2, m3and m4 of FIGS. 24, 28, 32, 36 and 40 schematically show zoom movementsof a first lens unit Gr1, a second lens unit Gr2, an aperture diaphragmS and a third lens unit Gr3, and a fourth lens unit Gr4 from thewide-angle limit [W] to the telephoto limit [T]. Arrow m5 of FIG. 28schematically shows the zoom movement of a fifth lens unit Gr5 from thewide-angle limit [W] to the telephoto limit [T].

Zoom lens systems of the fifth and seventh to ninth embodiments consistof, from the object side, a first lens unit Gr1 having a positiverefractive power, a second lens unit Gr2 having a negative refractivepower, a third lens unit Gr3 having a positive refractive power and afourth lens unit Gr4 having a positive refractive power, wherein zoomingis performed by varying the distances between the lens units.

In the fifth embodiment, image blur compensation is made by paralleldecentering (i.e. by moving vertically to the optical axis AX) a singlelens which is a second lens element of the second lens unit Gr2 as animage blur compensating lens element DL. In FIG. 24, arrow C representsthe movement of the second lens element of the second lens unit Gr2during image blur correction. In the seventh embodiment, image blurcompensation is made by parallel decentering a single lens which is afirst lens element of the third lens unit Gr3 as the image blurcompensating lens element DL. In FIG. 32, arrow C represents themovement of the first lens element of the third lens unit Gr3 duringimage blur correction. In the eighth embodiment, image blur compensationis made by parallel decentering a single lens which is a first lenselement of the fourth lens unit Gr4 as the image blur compensating lenselement DL. In FIG. 36, arrow C represents the movement of the firstlens element of the fourth lens unit Gr4 during image blur correction.In the ninth embodiment, image blur compensation is made by paralleldecentering a single lens which is a fourth lens element of the secondlens unit Gr2 as the image blur compensating lens element DL. In FIG.40, arrow C represents the movement of the fourth lens element of thesecond lens unit Gr2 during image blur correction.

In the seventh and eighth embodiments, the image side surface of theimage blur compensating lens element DL is an aspherical surface (i.e.r16 in the seventh embodiment, and r22 in the eighth embodiment), andthe lens disposed directly on the image side of the image blurcompensating lens element DL has an aspherical surface (i.e. r17 in theseventh embodiment, and r23 in the eighth embodiment) which cancels theaspherical surface of the image blur compensating lens element DL. Thatis, the facing surfaces are aspherical surfaces which cancel each other.By this arrangement, aberrations caused at the time of image blur areexcellently corrected without any change in the image quality to beobtained in normal photographing.

A zoom lens system of the sixth embodiment consists of, from the objectside, a first lens unit Gr1 having a positive refractive power, a secondlens unit Gr2 having a negative refractive power, a third lens unit Gr3having a positive refractive power, a fourth lens unit Gr4 having apositive refractive power and a fifth lens unit Gr5 having a negativerefractive power, wherein zooming is performed by varying the distancesbetween the lens units. Image blur compensation is made by paralleldecentering a doublet lens which is a fourth lens element of the secondlens unit Gr2 as the image blur compensating lens element DL. In FIG.28, arrow C represents the movement of the fourth lens element of thesecond lens unit Gr2 during image blur correction.

The fifth to ninth embodiments include from the object side the firstlens unit Gr1 having a positive refractive power, the second lens unitGr2 having a negative refractive power, the third lens unit Gr3 having apositive refractive power and the fourth lens unit Gr4 having a positiverefractive power so that they are suitable for use as the standard zoomlens systems and the standard high-magnification zoom lens systems forsingle lens reflex cameras. In this type of zoom lens systems includingpositive, negative, positive, positive lens units, the degree of freedomof the movements of the zoom lens units is effectively used foraberration correction. As a result, excellent image quality is obtainedin the entire zoom range even though the zoom lens systems arehigh-magnification zoom lens systems including the wide-angle range.

Since the first lens unit Gr1 and the fourth lens unit Gr4 are movedtoward the object side during zooming from the wide-angle limit [W] tothe telephoto limit [T], the zoom lens systems is in a retro-typearrangement at the wide-angle limit [W] and in a telephoto-typearrangement at the telephoto limit [T]. For this reason, a sufficientback focal length is secured and an optical system being short in totallength is achieved. Further, by arranging so that the second lens unitGr2 and the third lens unit Gr3 are moved toward the object side duringzooming from the wide-angle limit [W] to the telephoto limit [T], thedegree of freedom of the movements of the zoom lens units increases, sothat an optical system is obtained which is advantageous in correctingaberration and has a further reduced total length.

The fifth to ninth embodiments fulfill the following condition (6):

0.65<fR/fW<1.8  (6)

where fR is the composite focal length of the third lens unit Gr3 andthe entire lens units provided at an image side of the third lens unitGr3 at the wide-angle limit [W], and fW is the focal length of theentire lens system at the wide-angle limit [W].

The condition (6) relates to the composite focal length of the thirdlens unit Gr3 and succeeding lens units at the wide-angle limit [W]. Byfulfilling the condition (6), a high-magnification zoom lens systemincluding the wide-angle range is reduced in size and its image qualityis improved. When the upper limit of the condition (6) is exceeded,although this is advantageous in correcting aberrations, the structurallength of the third lens unit Gr3 and succeeding lens units increases,so that compactness is lost. When the condition (6) is fulfilled with anupper limit of 1.3, a more compact optical system is obtained. When thelower limit of the condition (6) is exceeded, the composite focal lengthof the third lens unit Gr3 and succeeding lens units at the wide-anglelimit [W] is too short, so that an excessive amount of aberration iscaused and it is difficult to correct the aberration by use of otherzoom lens units. When the condition (6) is fulfilled with a lower limitof 0.8, more excellent image quality is obtained.

The fifth to ninth embodiment further fulfill the following condition(7):

2.1<f1/fW<4.3  (7)

where f1 is the focal length of the first lens unit Gr1, and fW is thefocal length of the entire lens system at the wide-angle limit [W].

The condition (7) relates to the focal length of the first lens unitGr1. By fulfilling the condition (7), excellent image quality isobtained without any degradation in compactness. When the upper limit ofthe condition (7) is exceeded, the focal length of the first lens unitGr1 increases. Although this is advantageous in correcting aberrations,the diameter and the zoom movement amount of the first lens unit Gr1increases, so that it is difficult to obtain a compact optical system.When the condition (7) is fulfilled with an upper limit of 3.8, a morecompact optical system is obtained. When the lower limit of thecondition (7) is exceeded, the amount of aberration caused in the firstlens unit Gr1 is great and it is difficult to correct the aberration byuse of another lens unit. When the condition (7) is fulfilled with alower limit of 2.5, more excellent image quality is obtained.

As mentioned above, in zoom taking optical systems for single lensreflex cameras, it is typical that the first lens unit Gr1 is thelargest lens unit and is considerably heavy in weight. Therefore, inzoom lens systems like the fifth to ninth embodiments including from theobject side the first lens unit Gr1 having a positive refractive power,the second lens unit Gr2 having a negative refractive power, the thirdlens unit Gr3 having a positive refractive power and the fourth lensunit Gr4 having a positive refractive power, the first lens unit Gr1 isheavy in weight compared with the second lens unit Gr2 and succeedinglens units. For this reason, it is undesirable to make image blurcompensation by moving the first lens unit Gr1 vertically to the opticalaxis AX (i.e. by parallel decentering it) because this requires for theimage blur compensation driving system to increase in size.

In zoom lens systems like the fifth to ninth embodiments including fromthe object side the first lens unit Gr1 having a positive refractivepower, the second lens unit Gr2 having a negative refractive power, thethird lens unit Gr3 having a positive refractive power and the fourthlens unit Gr4 having a positive refractive power, it is typical that anaperture diaphragm S is disposed in the second lens unit Gr2 or in thethird lens unit Gr3. Since the axial luminous flux and the off-axialluminous flux are close to each other in the vicinity of the aperturediaphragm S, the lens diameter is small in the vicinity of the aperturediaphragm S. Since the second lens unit Gr2 and succeeding zoom lensunits are situated in the vicinity of the aperture diaphragm S duringzooming from the wide-angle limit [W] to the telephoto limit [T], theirlens diameters can be comparatively small. Therefore, using for imageblur compensation a small and lightweight lens element included in anyof the second lens unit Gr2 and succeeding zoom lens units like in thefifth to ninth embodiments is suitable for making image blurcompensation without increasing the burden on the image blurcompensation driving system.

However, if image blur compensation is made by parallel decentering aplurality of lens elements, since the weight of the lens elements to bedecentered and the lens frame is heavy, the burden on the image blurcompensation driving system increases. Therefore, in the fifth to ninthembodiments, image blur compensation is made by moving one lens elementvertically to the optical axis AX (i.e. by parallel decentering it). Bythis arrangement, the weight of the lens element to be decentered andthe lens frame is reduced, so that the burden on the image blurcompensation driving system is lightened.

With respect to the positional relationship between the aperturediaphragm S and one lens element (i.e. the image blur compensating lenselement) DL parallel decentered for image blur compensation, the fifthto ninth embodiments fulfill the following condition (8) in the entirezoom range:

D/f<1.2  (8)

where D is the distance from the aperture diaphragm S side surface ofthe image blur compensating lens element DL to the aperture diaphragm S,and f is the focal length of the entire lens system.

When the upper limit of the condition (8) is exceeded, the image blurcompensating lens element DL is largely away from the aperture diaphragmS, so that the position of passage of the axial luminous flux and thatof the off-axial luminous flux are largely away from each other.Consequently, the lens diameter increases to increase the lens weight.As a result, the burden on the image blur compensation driving systemincreases.

Generally, the aberration caused at the time of image blur isrepresented by the composition of the aberration caused in the opticalsystems preceding the optical system decentered for image blurcompensation and the aberration caused in the optical system decenteredfor image blur compensation. In the case where image blur compensationis made by one lens element DL like in the fifth to ninth embodiments,the optical systems preceding the image blur compensating lens elementDL have a higher degree of freedom of aberration correction than theimage blur compensating lens element DL because they include more lenselements. Therefore, the aberration caused in the normal condition andthe aberration caused at the time of image blur can both be corrected bythe optical systems preceding the image blur compensating lens elementDL. However, since the image blur compensating lens element DL has a lowdegree of freedom of aberration correction, if its refractive power istoo strong, the amount of aberration caused in the image blurcompensating lens element DL is great, so that it is difficult torestrain the aberration caused in the normal condition by use of otherlenses.

Therefore, in the fifth to ninth embodiments, the image blurcompensating lens element DL fulfill the following condition (9):

|Pd|/fW<2.30  (9)

where Pd is the refractive power of the image blur compensating lens DLelement.

When the upper limit of the condition (9) is exceeded, the refractivepower of the image blur compensating lens element DL is too strong, sothat an excessive amount of aberration is caused in the image blurcompensating lens element DL. As a result, it is difficult to correctthe aberration caused in the normal condition (pre-decenteredcondition). When the condition (9) is fulfilled with an upper limit of1.6, an optical system having its aberration further corrected isobtained.

In the sixth embodiment, the image blur compensating lens element DL isa doublet lens as mentioned above. This will be described in detail.When the image blur compensating lens element DL is parallel decenteredat the time of image blur, axial lateral chromatic aberration which isone of the decentering aberrations is caused. To restrain this, it isdesirable that the image blur compensating lens unit be color-corrected.However, when the image blur compensating lens element DL is one singlelens, chromatic aberration is inevitably caused in the image blurcompensating lens element DL. If the number of lens elements for imageblur compensation is increased to restrain this, the optical systemdecentered for image blur compensation increases in size. Therefore, itis desirable to use as the image blur compensating lens element DL adoublet lens formed of a positive lens and a negative lens. By using onedoublet lens, a color-corrected and lightweight image blur compensatinglens element DL is realized.

In the case where an image blur compensating lens element DL formed ofone doublet lens is used, when the image blur compensating lens elementDL has a positive refractive power, it is desirable for the image blurcompensating lens element DL to fulfill the following condition (10),and when the image blur compensating lens element DL has a negativerefractive power, it is desirable for the image blur compensating lenselement DL to fulfill the following condition (11):

νp>νn  (10)

νp<νn  (11)

where νp is the Abbe number of the positive lens element of the imageblur compensating lens element (doublet lens) DL, and νn is the Abbenumber of the negative lens element of the image blur compensating lenselement (doublet lens) DL.

When a lens unit is moved vertically to the optical axis AX for imageblur compensation, in the compensated condition (post-decenteringcondition), the light passes through a place where no light passes inthe normal condition (pre-decentering condition). There is a possibilitythat the light becomes harmful light and degrades the image quality.Therefore, it is desirable to cut off the harmful light during imageblur compensation by providing a stationary aperture diaphragm S on theobject side of the image blur compensating lens unit, in the image blurcompensating lens unit or on the image side of the image blurcompensating lens unit. By doing so, excellent image quality is obtainedin the image blur compensated condition.

Tables 6 to 10 show construction data of the fifth to ninth embodiments(FIGS. 24, 28, 32, 36 and 40). Table 11 shows values of the conditions(6) to (9) in the fifth to ninth embodiments.

In Tables 6 to 10 (and also in Tables 16 and 17, 20 to 23, 25 to 27,which will be described later), the surfaces whose radii of curvatureare marked with asterisks are aspherical surfaces defined by thefollowing expression (AS) representing the surface configuration of theaspherical surface:

 X=C·Y²/{1+(1−ε·C²·Y²)^(½)}+A4·Y⁴+A6·Y⁶+A8·Y⁸+A10 ·Y¹⁰+A12·Y¹²  (AS)

where X is a displacement amount from the reference surface in thedirection of the optical axis AX, Y is a height in the directionvertical to the optical axis AX, C is a paraxial curvature, E is a conicconstant, and A4, A6, A8, A10 and A12 are fourth-order, sixth-order,eighth-order, tenth-order and twelfth-order aspherical coefficients,respectively.

FIGS. 25A to 25I, 29A to 29I, 33A to 33I, 37A to 37I and 41A to 41I showlongitudinal aberration curves of the fifth to ninth embodiments. FIGS.25A to 25C, 29A to 29C, 33A to 33C, 37A to 37C and 41A to 41C showaberration curves at the wide-angle limit [W] in the normal condition(pre-decentering condition). FIGS. 25D to 25F, 29D to 29F, 33D to 33F,37D to 37F and 41D to 41F show aberration curves at the middle focallength condition [M] in the normal condition. FIGS. 25G to 25I, 29G to29I, 33G to 33I, 37G to 37I and 41G to 41I show aberration curves at thetelephoto limit [T] in the normal condition.

FIGS. 25A, 25D, 25G, 29A, 29D, 29G, 33A, 33D, 33G, 37A, 37D, 37G, 41A,41D and 41G show spherical aberration and sine condition. The solid lined represents aberration to the d-line. The broken line SC representssine condition. FIGS. 25B, 25E, 25H, 29B, 29E, 29H, 33B, 33E, 33H, 37B,37E, 37H, 41B, 41E and 41H show astigmatism. The broken line DM and thesolid line DS represent astigmatisms on the meridional image plane andon the sagittal image plane, respectively. FIGS. 25C, 25F, 25I, 29C,29F, 29I, 33C, 33F, 33I, 37C, 37F, 37I, 41C, 41F and 41I showdistortion.

FIGS. 26A to 26E, 30A to 30E, 34A to 34E, 38A to 38E and 42A to 42E showlateral aberration curves of the fifth to ninth embodiments at thewide-angle limit [W]. FIGS. 27A to 27E, 31A to 31E, 35A to 35E, 39A to39E and 43A to 43E show lateral aberration curves of the fifth to ninthembodiments at the telephoto limit [T].

FIGS. 26A, 26B, 27A, 27B, 30A, 30B, 31A, 31B, 34A, 34B, 35A, 35B, 38A,38B, 39A, 39B, 42A, 42B, 43A and 43B show lateral aberration (imageheight Y′=12, 0) with respect to the luminous flux on the meridionalimage plane before the decentering of the image blur compensating lenselement DL in the fifth to ninth embodiments. FIGS. 26C to 26E, 27C to27E, 30C to 30E, 31C to 31E, 34C to 34E, 35C to 35E, 38C to 38E, 39C to39E, 42C to 42E, 43C to 43E show lateral aberration (image heightY′=−12, 12, 0) with respect to the luminous flux on the meridional imageplane after the decentering of the second lens unit Gr2 in the fifth toninth embodiments. The aberration curves after the decentering showaberrations in the compensated condition when an image blur compensationangle θ of the second lens unit Gr2 is 0.7° (=0.0122173 rad.).

As described above, in the fifth to ninth embodiments, since the imageblur compensating lens element DL decentered for image blur compensationis one lightweight single lens or doublet lens included in any of thesecond to fourth lens units Gr2 to Gr4, the burden on the image blurcompensation driving system is light. In addition, since the powerarrangement and the zoom movement arrangement are effective in reducingthe total length to achieve compactness and the above-describedconditions are fulfilled, high description quality is obtained withoutany degradation of compactness.

<Tenth to Fifteenth Embodiments>

Zoom lens systems having an image blur compensating function accordingto the tenth to fifteenth embodiments will be described with referenceto the drawings. FIGS. 44, 48, 52, 56, 60 and 64 show the lensarrangements of the tenth to fifteenth embodiments in the normalcondition (pre-decentering condition) at the wide-angle limit [W]. Inthe figures, the surface marked with ri (i=1, 2, 3, . . . ) is an ithsurface counted from the object side, and the axial distance marked withdi (i=1, 2, 3, . . . ) is an ith axial distance counted from the objectside. Arrows m1, m2, m3 and m4 of FIGS. 44, 48, 52, 56, 60 and 64schematically show zoom movements of a first lens unit Gr1, a secondlens unit Gr2, an aperture diaphragm S and a third lens unit Gr3, and afourth lens unit Gr4 from the wide-angle limit [W] to the telephotolimit [T]. Arrow m5 of FIG. 64 schematically shows the zoom movement ofa fifth lens unit Gr5 from the wide-angle limit [W] to the telephotolimit [T].

Zoom lens systems of the tenth to fourteenth embodiments consist of,from the object side, a first lens unit Gr1 having a positive refractivepower, a second lens unit Gr2 having a negative refractive power, athird lens unit Gr3 having a positive refractive power and a fourth lensunit Gr4 having a negative refractive power, wherein zooming isperformed by varying the distances between the lens units. In the tenth,eleventh and fourteenth embodiments, the second lens unit Gr2 is dividedinto a front lens unit GrA and a rear lens unit GrB from the objectside, and image blur compensation is made by parallel decentering thefront lens unit GrA (i.e. by moving it vertically to the optical axisAX). In FIGS. 44, 48, and 60, arrow C represents the movement of thefront lens unit GrA during image blur correction. In the twelfth andthirteenth embodiments, the second lens unit is divided into a frontlens unit GrA and a rear lens unit GrB from the object side, and imageblur compensation is made by parallel decentering the rear lens unitGrB. In FIGS. 52, and 56, arrow C represents the movement of the rearlens unit GrB during image blur correction. In the fourteenthembodiment, the facing surfaces (i.e. r8 and r9) of the front and rearlens units GrA and GrB are aspherical surfaces which cancel each other.By this arrangement, aberrations caused at the time of image blur areexcellently corrected without any change in the image quality to beobtained in normal photographing.

A zoom lens system of the fifteenth embodiment consists of, from theobject side, a first lens unit Gr1 having a positive refractive power, asecond lens unit Gr2 having a negative refractive power, a third lensunit Gr3 having a positive refractive power, a fourth lens unit Gr4having a positive refractive power and a fifth lens unit Gr5 having anegative refractive power, wherein zooming is performed by varying thedistances between the lens units. In the fifteenth embodiment, thesecond lens unit Gr2 is divided into a front lens unit GrA and a rearlens unit GrB from the object side, and image blur compensation is madeby parallel decentering the rear lens unit GrB. In FIG. 64, arrow Crepresents the movement of the rear lens unit GrB during image blurcorrection.

The tenth to fifteenth lens units include from the object side the firstlens unit Gr1 having a positive refractive power and the second lensunit Gr2 having a negative refractive power, and include on the mostimage side the last lens unit (i.e. the most image side lens unit)having a negative refractive power. In this type of zoom lens systems,since the degree of freedom of the movements of the zoom lens units iseffectively used for aberration correction, excellent image quality isobtained in the entire zoom range.

Since the first lens unit Gr1 and the last lens unit are moved towardthe object side during zooming from the wide-angle limit [W] to thetelephoto limit [T], a zoom optical system is realized which is compactbut has a sufficient back focal length. In a four-unit zoom lens systemof positive, negative, positive, negative configuration, by arranging sothat the first lens unit Gr1 and the fourth lens unit Gr4 are movedtoward the object side during zooming from the wide-angle limit [W] tothe telephoto limit [T] like in the tenth to fourteenth embodiments, anextremely compact telephoto zoom lens system is obtained. Further, byarranging so that the third lens unit Gr3 is moved toward the objectside during zooming from the wide-angle limit [W] to the telephoto limit[T], the degree of freedom of the movements of the zoom lens unitsincreases, so that an optical system is obtained which is advantageousin correcting aberration and has a further reduced total length.

The tenth to fifteenth embodiments fulfill the following condition (12):

 1.3<(fT/fW)·(βLW/βLT)<7.0  (12)

where fT is the focal length of the entire lens system at the telephotolimit [T], fW is the focal length of the entire lens system at thewide-angle limit [W], βLW is the magnification of the last lens unit atthe wide-angle limit [W], and βLT is the magnification of the last lensunit at the telephoto limit [T].

The condition (12) shows how much the last lens unit contributes tozooming. When the upper limit of the condition (12) is exceeded, theproportion of the contribution of the last lens unit to zoomingdecreases, so that the compactness of the entire zoom lens system islost. When the condition (12) is fulfilled with an upper limit of 3.0, amore compact zoom lens system is obtained. When the lower limit of thecondition (12) is exceeded, zooming is performed mostly by the last lensunit, so that the variation in aberration caused by zooming increasesand it is difficult to restrain it. When the condition (12) is fulfilledwith a lower limit of 1.45, a zoom lens system which is more excellentin image quality is obtained.

In zoom taking optical systems for single lens reflex cameras, it istypical that the first lens unit Gr1 is the largest lens unit and isconsiderably heavy in weight. Therefore, in zoom lens systems like thetenth to fifteenth embodiments including from the object side the firstlens unit Gr1 having a positive refractive power and the second lensunit Gr2 having a negative refractive power, and including on the mostimage side the last lens unit having a negative refractive power whereinzooming is performed by varying the distances between the lens units andthe first lens unit Gr1 and the last lens unit are moved toward theobject side during zooming from the wide-angle limit [W] to thetelephoto limit [T], the first lens unit Gr1 is heavy in weight comparedwith the second lens unit Gr2 and succeeding lens units. For thisreason, it is undesirable to make image blur compensation by moving thefirst lens unit Gr1 vertically to the optical axis AX (i.e. by paralleldecentering it) because this requires the image blur compensationdriving system to increase in size.

In zoom lens systems like the tenth to fifteenth embodiments includingfrom the object side the first lens unit Gr1 having a positiverefractive power and the second lens unit Gr2 having a negativerefractive power and including on the most image side the last lens unithaving a positive refractive power wherein zooming is performed byvarying the distances between the lens units and the first lens unit Gr1and the last lens unit are moved toward the object side during zoomingfrom the wide-angle limit [W] to the telephoto limit [T], it is typicalthat the aperture diaphragm S is disposed in the second lens unit Gr2 orin the third lens unit Gr3. Since the axial luminous flux and theoff-axial luminous flux are close to each other in the vicinity of theaperture diaphragm S, the lens diameter is small in the vicinity of theaperture diaphragm S. Since the second lens unit Gr2 is situated in thevicinity of the aperture diaphragm S during zooming from the wide-anglelimit [W] to the telephoto limit [T], its lens diameter can becomparatively small. Therefore, the use of the small and lightweightsecond lens unit Gr2 for image blur compensation is suitable for makingimage blur compensation without increasing the burden on the image blurcompensation driving system.

However, if image blur compensation is made by parallel decentering theentire second lens unit Gr2, the weight of the lens to be paralleldecentered and the lens frame increases, so that the burden on the imageblur compensation driving system increases. Therefore, in the tenth tofifteenth embodiments, the second lens unit Gr2 is divided into thefront lens unit GrA and the rear lens unit GrB from the object side, andimage blur compensation is made by moving the front lens unit GrA or therear lens unit GrB of the second lens unit Gr2 vertically to the opticalaxis (i.e. by parallel decentering it) as the image blur compensatinglens unit. By this arrangement, the weight of the lens moved for imageblur compensation and the lens frame are reduced, so that the burden onthe image blur compensation driving system is lightened.

If a lens unit which is largely moved during zooming is used for imageblur compensation, it is necessary to largely move the image blurcompensating means together with the image blur compensating lens unit,so that the moving means is largely burdened during zooming. The zoommovement amount of the second lens unit is extremely small compared withthe other lens units. Therefore, also in this regard, it is advantageousto use the front lens unit GrA or the rear lens unit GrB of the secondlens unit Gr2 as the image blur compensating lens unit.

It is desirable that the movement amount of the image blur compensatinglens unit at the time of image blur (i.e. image blur compensationmovement amount) at the wide-angle limit [W] and that at the telephotolimit [T] do not largely differ from each other. Therefore, the tenth tofifteenth embodiments further fulfill the following condition (13):

0.4<MT/MW<2.5  (13)

where MT is the blur compensation movement amount of either of the frontor the rear lens unit moving vertically to an optical axis to compensatefor an image blur at the telephoto limit [T], and MW is the blurcompensation movement amount of either of the front or the rear lensunit moving vertically to an optical axis to compensate for an imageblur at the wide-angle limit [W].

When the upper limit or the lower limit of the condition (13) isexceeded, the image blur compensation movement amount at the wide-anglelimit [W] and that at the telephoto limit [T] largely differ from eachother, so that error is prone to be caused in calculating the image blurcompensation amount at a given focal length.

When the image blur compensating lens unit is parallel decentered at thetime of image blur, axial lateral chromatic aberration which is one ofthe decentering aberrations is caused. To restrain this, it is desirablethat the image blur compensating lens unit be color-corrected.Therefore, the tenth to fifteenth embodiments further fulfill thefollowing condition (14):

νp>νn  (14)

where νp is the Abbe number of the positive lens element included ineither of the front or the rear lens unit moving vertically to anoptical axis to compensate for an image blur, and νn is the Abbe numberof the negative lens element included in either of the front or the rearlens unit moving vertically to an optical axis to compensate for animage blur.

When a lens unit is moved vertically to the optical axis AX for imageblur compensation, in the compensated condition (post-decenteringcondition), the light passes through a place where no light passes inthe normal condition (pre-decentering condition). There is a possibilitythat the light becomes harmful light and degrades the image quality.Therefore, it is desirable to cut off the harmful light during imageblur compensation by providing a stationary aperture diaphragm S on theobject side of the image blur compensating lens unit, in the image blurcompensating lens unit or on the image side of the image blurcompensating lens unit. By doing so, excellent image quality is obtainedin the image blur compensated condition.

Tables 12 to 17 show construction data of the tenth to fifteenthembodiments (FIGS. 44, 48, 52, 56, 60 and 64). Table 18 shows values ofthe conditions (12) and (13) in the tenth to fifteenth embodiments.Table 19 shows data on refractive power in the tenth to fifteenthembodiments. In Table 19, φ1 is the refractive power of the first lensunit, φ2 is the refractive power of the second lens unit, and φL is therefractive power of the last lens unit.

FIGS. 45A to 45I, 49A to 49I, 53A to 53I, 57A to 57I, 61A to 61I and 65Ato 65I show longitudinal aberration curves of the tenth to fifteenthembodiments. FIGS. 45A to 45C, 49A to 49C, 53A to 53C, 57A to 57C, 61Ato 61C and 65A to 65C show aberration curves at the wide-angle limit [W]in the normal condition (pre-decentering condition). FIGS. 45D to 45F,49D to 49F, 53D to 53F, 57D to 57F, 61D to 61F and 65D to 65F showaberration curves at the middle focal length condition [M] in the normalcondition. FIGS. 45G to 45I, 49G to 49I, 53G to 53I, 57G to 57I, 61G to61I and 65G to 65I show aberration curves at the telephoto limit [T] inthe normal condition.

FIGS. 45A, 45D, 45G, 49A, 49D, 49G, 53A, 53D, 53G, 57A, 57D, 57G, 61A,61D, 61G, 65A, 65D and 65G show spherical aberration and sine condition.The solid line d represents aberration to the d-line. The broken line SCrepresents sine condition. FIGS. 45B, 45E, 45H, 49B, 49E, 49H, 53B, 53E,53H, 57B, 57E, 57H, 61B, 61E, 61H, 65B, 65E and 65H show astigmatism.The broken line DM and the solid line DS represent astigmatisms on themeridional image plane and on the sagittal image plane, respectively.FIGS. 45C, 45F, 45I, 49C, 49F, 49I, 53C, 53F, 53I, 57C, 57F, 57I, 61C,61F, 61I, 65C, 65F and 65I show distortion.

FIGS. 46A to 46E, 50A to 50E, 54A to 54E, 58A to 58E, 62A to 62E and 66Ato 66E show lateral aberration curves of the tenth to fifteenthembodiments at the wide-angle limit [W]. FIGS. 47A to 47E, 51A to 51E,55A to 55E, 59A to 59E, 63A to 63E and 67A to 67E show lateralaberration curves of the tenth to fifteenth embodiments at the telephotolimit [T].

FIGS. 46A, 46B, 47A, 47B, 50A, 50B, 51A, 51B, 54A, 54B, 55A, 55B, 58A,58B, 59A, 59B, 62A, 62B, 63A, 63B, 66A, 66B, 67A and 67B show lateralaberration (image height Y′=12, 0) with respect to the luminous flux onthe meridional image plane before the decentering of the image blurcompensating lens unit in the tenth to fifteenth embodiments. FIGS. 26Cto 26E, 27C to 27E, 30C to 30E, 31C to 31E, 34C to 34E, 35C to 35E, 38Cto 38E, 39C to 39E, 42C to 42E and 43C to 43E show lateral aberration(image height Y′=−12, 12, 0) with respect to the luminous flux on themeridional image plane after the decentering of the image blurcompensating lens unit in the tenth to fifteenth embodiments. Theaberration curves after the decentering show aberrations in thecompensated condition when an image blur compensation angle θ of theimage blur compensating lens unit is 0.7° (=0.0122173 rad.).

As described above, in the tenth to fifteenth embodiments, since theimage blur compensating lens unit parallel decentered for image blurcompensation is the lightweight front or rear lens unit GrA or GrBincluded in the second lens unit Gr2, the burden on the image blurcompensation driving system is lightened. In addition, the zoommovements of the lens units and the power arrangement are effective inreducing the total length to achieve compactness.

<Sixteenth to Nineteenth Embodiments>

Zoom lens systems having an image blur compensating function accordingto the sixteenth to nineteenth embodiments will be described withreference to the drawings. FIGS. 68, 72, 76 and 80 show the lensarrangements of the sixteenth to nineteenth embodiments in the normalcondition (pre-decentering condition) at the wide-angle limit [W]. Inthe figures, the surface marked with ri (i=1, 2, 3, . . . ) is an ithsurface counted from the object side, and the axial distance marked withdi (i=1, 2, 3, . . . ) is an ith axial distance counted from the objectside. Arrows m1, m2, m3 and m4 of FIGS. 68, 72, 76 and 80 schematicallyshow zoom movements of a first lens unit Gr1, a second lens unit r2, anaperture diaphragm S and a third lens unit Gr3, and a fourth lens unitGr4 from the wide-angle limit [W] to the telephoto limit [T]. Arrow m5of FIG. 68 schematically shows the zoom movement of a fifth lens unitGr5 from the wide-angle limit [W] to the telephoto limit [T].

A zoom lens system of the sixteenth embodiment consists of, from theobject side, a first lens unit Gr1 having a positive refractive power, asecond lens unit Gr2 having a negative refractive power, a third lensunit Gr3 having a positive refractive power, a fourth lens unit Gr4having a positive refractive power and a fifth lens unit Gr5 having anegative refractive power wherein zooming is performed by varying thedistances between the lens units. In the sixteenth embodiment, thesecond lens unit Gr2 is divided into a front lens unit GrA and a rearlens unit GrB from the object side, and image blur compensation is madeby parallel decentering the rear lens unit GrB (i.e. moving itvertically to the optical axis AX). In FIG. 68, arrow C represents themovement of the rear lens unit GrB during image blur correction.

Zoom lens systems of the seventeenth to nineteenth embodiments are zoomlens systems consisting of, from the object side, a first lens unit Gr1having a positive refractive power, a second lens unit Gr2 having anegative refractive power, a third lens unit Gr3 having a positiverefractive power and a fourth lens unit Gr4 having a positive refractivepower wherein zooming is performed by varying the distances between thelens units.

In the seventeenth embodiment, the third lens unit Gr3 is divided into afront lens unit GrA and a rear lens unit GrB from the object side, andimage blur compensation is made by parallel decentering the front lensunit GrA. In FIG. 72, arrow C represents the movement of the front lensunit GrA during image blur correction. In the eighteenth embodiment, thefourth lens unit Gr4 is divided into a front lens unit GrA and a rearlens unit GrB from the object side, and image blur compensation is madeby parallel decentering the front lens unit GrA. In FIG. 76, arrow Crepresents the movement of the front lens unit GrA during image blurcorrection. In the nineteenth embodiment, the second lens unit Gr2 isdivided into a front lens unit GrA and a rear lens unit GrB from theobject side, and image blur compensation is made by parallel decenteringthe rear lens unit GrB. In FIG. 80, arrow C represents the movement ofthe rear lens unit GrB during image blur correction.

In the seventeenth and eighteenth embodiments, the image side surface ofthe front lens unit GrA serving as the image blur compensating lens unitis an aspherical surface (i.e. r16 in the seventeenth embodiment, andr22 in the eighteenth embodiment), and the lens disposed directly on theimage side of the front lens unit GrA has an aspherical surface (i.e.r17 in the seventeenth embodiment, and r23 in the eighteenth embodiment)which cancels the aspherical surface of the front lens unit GrA. Thatis, the facing surfaces of the front and rear lens units GrA and GrB areaspherical surfaces which cancel each other. By this arrangement,aberrations caused at the time of image blur are excellently correctedwithout any change in the image quality to be obtained in normalphotographing.

The sixteenth to nineteenth embodiments include from the object side thefirst lens unit Gr1 having a positive refractive power, the second lensunit Gr2 having a negative refractive power and the third lens unit Gr3having a positive refractive power so that they are suitable for use asthe standard zoom lens systems and the standard high-magnification zoomlens systems for single lens reflex cameras. In this type of zoom lenssystems including positive, negative, positive lens units, the degree offreedom of the movements of the zoom lens units is effectively used foraberration correction. As a result, excellent image quality is obtainedin the entire zoom range even though the zoom lens systems arehigh-magnification zoom lens systems including the wide-angle range.

Since the first lens unit Gr1 is moved toward the object side duringzooming from the wide-angle limit [W] to the telephoto limit [T], thezoom lens systems is in a retro-type arrangement at the wide-angle limit[W] and in a telephoto-type arrangement at the telephoto limit [T]. Forthis reason, a sufficient back focal length is secured and an opticalsystem being short in total length is achieved. Further, by arranging sothat the second lens unit Gr2 and the third lens unit Gr3 are movedtoward the object side during zooming from the wide-angle limit [W] tothe telephoto limit [T], the degree of freedom of the movements of thezoom lens units increases, so that an optical system is obtained whichis advantageous in correcting aberration and has a further reduced totallength.

In this type of zoom lens systems, since the zoom lens units positivelyperform zooming, the aberration burden on the zoom lens units isconsiderably heavy. For this reason, it is extremely difficult tocorrect aberrations caused in each of the zoom lens units by use of onlyone single lens or one doublet lens. Therefore, it is desirable that thezoom lens units include a plurality of lens elements.

The sixteenth to nineteenth embodiments fulfill the conditions (6) to(11) noted above. When the condition (6) is fulfilled with an upperlimit of 1.3, a more compact optical system is obtained; when thecondition (6) is fulfilled with a lower limit of 0.8, still better imagequality is obtained. When the condition (7) is fulfilled with an upperlimit of 3.8, a more compact optical system is obtained; when thecondition (7) is fulfilled with a lower limit of 2.5, still better imagequality is obtained. Moreover, when the condition (9) is fulfilled withan upper limit of 1.6, an optical system having its aberration furthercorrected is obtained.

Tables 20 to 23 show construction data of the sixteenth to nineteenthembodiments (FIGS. 68, 72, 76 and 80). Table 24 shows values of theconditions (6) to (9) in the sixteenth to nineteenth embodiments.

FIGS. 69A to 69I, 73A to 73I, 77A to 77I and 81A to 81I showlongitudinal aberration curves of the sixteenth to nineteenthembodiments. FIGS. 69A to 69C, 73A to 73C, 77A to 77C and 81A to 81Cshow aberration curves at the wide-angle limit [W] in the normalcondition (pre-decentering condition). FIGS. 69D to 69F, 73D to 73F, 77Dto 77F and 81D to 81F show aberration curves at the middle focal lengthcondition [M] in the normal condition. FIGS. 69G to 69I, 73G to 73I, 77Gto 77I and 81G to 81I show aberration curves at the telephoto limit [T]in the normal condition.

FIGS. 69A, 69D, 69G, 73A, 73D, 73G, 77A, 77D, 77G, 81A, 81D and 81G showspherical aberration and sine condition. The solid line d representsaberration to the d-line. The broken line SC represents sine condition.FIGS. 69B, 69E, 69H, 73B, 73E, 73H, 77B, 77E, 77H, 81B, 81E and 81H showastigmatism. The broken line DM and the solid line DS representastigmatisms on the meridional image plane and on the sagittal imageplane, respectively. FIGS. 69C, 69F, 69I, 73C, 73F, 73I, 77C, 77F, 77I,81C, 81F and 81I show distortion.

FIGS. 70A to 70E, 74A to 74E, 78A to 78E and 82A to 82E show lateralaberration curves of the sixteenth to nineteenth embodiments at thewide-angle limit [W]. FIGS. 71A to 71E, 75A to 75E, 79A to 79E and 83Ato 83E show lateral aberration curves of the sixteenth to nineteenthembodiments at the telephoto limit [T].

FIGS. 70A, 70B, 71A, 71B, 74A, 74B, 75A, 75B, 78A, 78B, 79A, 79B, 82A,82B, 83A and 83B show lateral aberration (image height Y′=12, 0) withrespect to the luminous flux on the meridional image plane before thedecentering of the image blur compensating lens unit in the sixteenth tonineteenth embodiments. FIGS. 70C to 70E, 71C to 71E, 74C to 74E, 75C to75E, 78C to 78E, 79C to 79E, 82C to 82E and 83C to 83E show lateralaberration (image height Y′=−12, 12, 0) with respect to the luminousflux on the meridional image plane after the decentering of the imageblur compensating lens unit in the sixteenth to nineteenth embodiments.The aberration curves after the decentering show aberrations in thecompensated condition when an image blur compensation angle θ of theimage blur compensating lens unit is 0.7° (=0.0122173 rad.).

As described above, in the sixteenth to nineteenth embodiments, sincethe image blur compensating lens unit parallel decentered for image blurcompensation is a lightweight front or rear lens unit GrA or GrBincluded in the second, third or fourth lens unit Gr2, Gr3 or Gr4, theburden on the image blur compensation driving system is lightened. Inaddition, since the power arrangement and the zoom movement arrangementare effective in reducing the total length to achieve compactness andthe above-described conditions are fulfilled, high description qualityis obtained without any degradation of compactness.

<Twentieth to Twenty-second Embodiments>

Zoom lens systems having an image blur compensating function accordingto the twentieth to twenty-second embodiments will be described withreference to the drawings. FIGS. 84, 88 and 92 show the lensarrangements of the twentieth to twenty-second embodiments in the normalcondition (pre-decentering condition) at the wide-angle limit [W]. Inthe figures, the surface marked with ri (i=1, 2, 3, . . . ) is an ithsurface counted from the object side, and the axial distance marked withdi (i=1, 2, 3, . . . ) is an ith axial distance counted from the objectside. Arrows m1, m2, m3 and m4 of FIGS. 84, 88 and 92 schematically showzoom movements of a first lens unit Gr1, a second lens unit Gr2, a thirdlens unit Gr3 and a fourth lens unit Gr4 from the wide-angle limit [W]to the telephoto limit [T].

Zoom lens systems of the twentieth to twenty-second embodiments are zoomlens systems consisting of, from the object side, a first lens unit Gr1having a positive refractive power, a second lens unit Gr2 having anegative refractive power, a third lens unit Gr3 having a positiverefractive power and a fourth lens unit Gr4 having a positive refractivepower wherein zooming is performed by varying the distances between thelens units.

In the twentieth embodiment, the third lens unit Gr3 is divided into afront lens unit GrA and a rear lens unit GrB from the object side, andimage blur compensation is made by parallel decentering the front lensunit GrA (i.e. by moving it vertically to the optical axis AX). In FIG.84, arrow C represents the movement of the front lens unit GrA duringimage blur correction. In the twenty-first embodiment, the fourth lensunit Gr4 is divided into a front lens unit GrA and a rear lens unit GrBfrom the object side, and image blur compensation is made by paralleldecentering the front lens unit GrA. In FIG. 88, arrow C represents themovement of the front lens unit GrA during image blur correction. In thetwenty-second embodiment, the second lens unit Gr2 is divided into afront lens unit GrA and a rear lens unit GrB from the object side, andimage blur compensation is made by parallel decentering the rear lensunit GrB. In FIG. 92, arrow C represents the movement of the rear lensunit GrB during image blur correction.

In the twentieth and twenty-first embodiments, the image side surface ofthe front lens unit GrA serving as the image blur compensating lens unitis an aspherical surface (i.e. r16 in the twentieth embodiment, and r22in the twenty-first embodiment), and the lens disposed directly on theimage side of the front lens unit GrA has an aspherical surface (i.e.r17 in the twentieth embodiment, and r23 in the twenty-first embodiment)which cancels the aspherical surface of the front lens unit GrA. Thatis, the facing surfaces of the front and rear lens units GrA and GrB areaspherical surfaces which cancel each other. By this arrangement,aberrations caused at the time of image blur are excellently correctedwithout any change in the image quality to be obtained in normalphotographing.

The zoom lens systems of the twentieth to twenty-second embodiments aresuitable for use as the zoom lens system for single lens reflex cameras.In this type of zoom lens systems consisting of four zoom lens units ofa positive, negative, positive configuration, the degree of freedom ofthe movements of the zoom lens units is effectively used for aberrationcorrection, so that excellent image quality is obtained in the entirezoom range.

Since the first lens unit Gr1 and the fourth lens unit Gr4 are movedtoward the object side during zooming from the wide-angle limit [W] tothe telephoto limit [T], the zoom lens systems is in a retro-typearrangement at the wide-angle limit [W] and in a telephoto-typearrangement at the telephoto limit [T]. For this reason, a sufficientback focal length is secured and an optical system being short in totallength is achieved. Further, by arranging so that the second lens unitGr2 and the third lens unit Gr3 are moved toward the object side duringzooming from the wide-angle limit [W] to the telephoto limit [T], thedegree of freedom of the movements of the zoom lens units increases, sothat an optical system is obtained which is advantageous in correctingaberration and has a further reduced total length.

Although the degree of freedom of aberration correction increases as thenumber of zoom lens units increases, the overall size of the opticalsystem (particularly, the size at the wide-angle limit [W]) increasesaccordingly. However, since the zoom lens systems of this type have fourlens units, the degree of freedom for restraining the aberrations causedduring zooming and the compactness of the optical system aresimultaneously satisfied. That is, if the number of zoom lens units issmaller than this, it is difficult to satisfy excellent image quality inthe entire zoom range, and conversely, if the number of zoom lens unitsis greater than this, it is difficult to maintain the compactness of theentire optical system and the structure of the lens barrel iscomplicated.

In this type of zoom lens systems, since the zoom lens units positivelyperform zooming, the aberration burden on the zoom lens units isconsiderably heavy. For this reason, it is extremely difficult tocorrect aberrations caused in the zoom lens units by use of only onesingle lens or one doublet lens. Therefore, it is desirable that thezoom lens units include a plurality of lens elements.

The twentieth to twenty-second embodiments fulfill the conditions (6) to(11) noted above. When the condition (6) is fulfilled with an upperlimit of 1.3, a more compact optical system is obtained; when thecondition (6) is fulfilled with a lower limit of 0.8, still better imagequality is obtained. When the condition (7) is fulfilled with an upperlimit of 3.8, a more compact optical system is obtained; when thecondition (7) is fulfilled with a lower limit of 2.5, still better imagequality is obtained. Moreover, when the condition (9) is fulfilled withan upper limit of 1.6, an optical system having its aberration furthercorrected is obtained.

Tables 25 to 27 show construction data of the twentieth to twenty-secondembodiments (FIGS. 84, 88, and 92). Table 28 shows values of theconditions (6) to (9) in the twentieth to twenty-second embodiments.

FIGS. 85A to 85I, 89A to 89I and 93A to 93I show longitudinal aberrationcurves of the twentieth to twenty-second embodiments. FIGS. 85A to 85C,89A to 89C and 93A to 93C show aberration curves at the wide-angle limit[W] in the normal condition (pre-decentering condition). FIGS. 85D to85F, 89D to 89F and 93D to 93F show aberration curves at the middlefocal length condition [M] in the normal condition. FIGS. 85G to 85I,89G to 89I and 93G to 93I show aberration curves at the telephoto limit[T] in the normal condition.

FIGS. 85A, 85D, 85G, 89A, 89D, 89G, 93A, 93D and 93G show sphericalaberration and sine condition. The solid line d represents aberration tothe d-line. The broken line SC represents sine condition. FIGS. 85B,85E, 85H, 89B, 89E, 89H, 93B, 93E and 93H show astigmatism. The brokenline DM and the solid line DS represent astigmatisms on the meridionalimage plane and on the sagittal image plane, respectively. FIGS. 85C,85F, 85I, 89C, 89F, 89I, 93C, 93F and 93I show distortion.

FIGS. 86A to 86E, 90A to 90E and 94A to 94E show lateral aberrationcurves of the twentieth to twenty-second embodiments at the wide-anglelimit [W]. FIGS. 87A to 87E, 91A to 91E and 95A to 95E show lateralaberration curves of the twentieth to twenty-second embodiments at thetelephoto limit [T].

FIGS. 86A, 86B, 87A, 87B, 90A, 90B, 91A, 91B, 94A, 94B, 95A and 95B showlateral aberration (image height Y′=12, 0) with respect to the luminousflux on the meridional image plane before the decentering of the imageblur compensating lens unit in the twentieth to twenty-secondembodiments. FIGS. 86C to 86E, 87C to 87E, 90C to 90E, 91C to 91E, 94Cto 94E and 95C to 95E show lateral aberration (image height Y′=−12, 12,0) with respect to the luminous flux on the meridional image plane afterthe decentering of the image blur compensating lens unit in thetwentieth to twenty-second embodiments. The aberration curves after thedecentering show aberrations in the compensated condition when an imageblur compensation angle θ of the image blur compensating lens unit is0.7° (=0.0122173 rad.).

As described above, in the twentieth to twenty-second embodiments, sincethe image blur compensating lens unit parallel decentered for image blurcompensation is a lightweight front or rear lens unit GrA or GrBincluded in the second, third or fourth lens unit Gr2, Gr3 or Gr4, theburden on the image blur compensation driving system is lightened. Inaddition, since the power arrangement and the zoom movement arrangementare effective in reducing the total length to achieve compactness andthe above-described conditions are fulfilled, high description qualityis obtained without any degradation of compactness.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced other than as specifically described.

TABLE 1 << Embodiment 1 >> f = 83.0˜160.0˜234.0 FNO = 4.60˜5.81˜5.78Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 97.345 d1 1.700 N1 1.61293 ν1 36.96 r2 48.265d2 6.460 N2 1.49310 ν2 83.58 r3 −1091.036 d3 0.100 r4 57.984 d4 3.820 N31.49310 ν3 83.58 r5 810.051 d5 3.300˜26.272˜39.846 <Second Lens UnitGr2-negative> r6 −73.346 d6 1.830 N4 1.71300 ν4 53.93 r7 34.239 d7 3.000r8 39.600 d8 2.750 N5 1.67339 ν5 29.25 r9 −3349.859 d9 2.000 r10 −35.714d10 1.215 N6 1.51728 ν6 69.43 r11 −29.097 d11 2.000˜4.000˜6.000 <ThirdLens Unit Gr3-negative> r12 −24.999 d12 1.215 N7 1.51728 ν7 69.43 r13−30.588 d13 20.453˜4.949˜1.000 <Aperture Diaphragm S, Fourth Lens UnitGr4-positive> r14 ∞ (Aperture Diaphragm S) d14 1.380 r15 60.430 d151.300 N8 1.84666 ν8 23.82 r16 26.308 d16 2.460 r17 41.552 d17 2.840 N91.51680 ν9 64.20 r18 −115.365 d18 0.400 r19 36.133 d19 4.550 N10 1.51680ν10 64.20 r20 −42.506 d20 19.811˜9.140˜0.900 <Fifth Lens UnitGr5-negative> r21 214.395 d21 1.080 N11 1.71300 ν11 53.93 r22 23.976 d221.540 r23 −181.698 d23 3.480 N12 1.67339 ν12 29.25 r24 −18.797 d24 1.130N13 1.75450 ν13 51.57 r25 ∞ Σd = 89.815˜88.611˜91.997

TABLE 2 << Embodiment 2 >> f = 82.6˜160.0˜234.0 FNO = 4.60˜5.81˜6.83Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 97.792 d1 1.700 N1 1.61293 ν1 36.96 r2 46.299d2 6.460 N2 1.49310 ν2 83.58 r3 −184.667 d3 0.100 r4 50.563 d4 3.820 N31.49310 ν3 83.58 r5 241.312 d5 3.300˜23.941˜31.837 <Second Lens UnitGr2-negative> r6 −71.122 d6 1.830 N4 1.71300 ν4 53.93 r7 33.113 d7 1.000r8 20.179 d8 2.000 N5 1.51728 ν5 69.43 r9 24.487 d9 2.000˜4.000˜6.000<Third Lens Unit Gr3-positive> r10 30.032 d10 1.215 N6 1.51728 ν6 69.43r11 19.448 d11 1.000 r12 26.836 d12 2.750 N7 1.67339 ν7 29.25 r13117.377 d13 23.629˜8.887˜1.306 <Aperture Diaphragm S, Fourth Lens UnitGr4-positive> r14 ∞ (Aperture Diaphragm S) d14 1.380 r15 73.885 d151.300 N8 1.84666 ν8 23.82 r16 28.089 d16 2.460 r17 46.118 d17 2.840 N91.51680 ν9 64.20 r18 −60.125 d18 0.400 r19 34.079 d19 4.550 N10 1.51680ν10 64.20 r20 −44.058 d20 17.850˜6.911˜0.874 <Fifth Lens UnitGr5-negative> r21 512.839 d21 1.080 N11 1.71300 ν11 53.93 r22 24.541 d221.540 r23 −133.326 d23 3.480 N12 1.67339 ν12 29.25 r24 −17.645 d24 1.130N13 1.75450 ν13 51.57 r25 ∞ Σd = 88.815˜85.775˜82.052

TABLE 3 << Embodiment 3 >> f = 82.6˜160.0˜234.0 FNO = 4.60˜5.81˜5.95Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 58.900 d1 1.700 N1 1.61293 ν1 36.96 r2 34.284d2 6.460 N2 1.49310 ν2 83.58 r3 −300.890 d3 0.100 r4 63.185 d4 3.820 N31.49310 ν3 83.58 r5 98.931 d5 3.300˜28.301˜41.700 <Second Lens UnitGr2-negative> r6 −74.716 d6 1.830 N4 1.71300 ν4 53.93 r7 29.553 d7 1.000r8 23.424 d8 1.215 N5 1.51728 ν5 69.43 r9 39.791 d9 2.500˜4.000˜7.500<Third Lens Unit Gr3-positive> r10 36.855 d10 1.215 N6 1.51728 ν6 69.43r11 21.931 d11 1.000 r12 29.252 d12 2.750 N7 1.67339 ν7 29.25 r13212.765 d13 29.756˜11.469˜1.306 <Aperture Diaphragm S, Fourth Lens UnitGr4-positive> r14 ∞ (Aperture Diaphragm S) d14 1.380 r15 62.924 d151.300 N8 1.84666 ν8 23.82 r16 28.043 d16 2.460 r17 45.986 d17 2.840 N91.51680 ν9 64.20 r18 −86.763 d18 0.400 r19 32.661 d19 4.550 N10 1.51680ν10 64.20 r20 −50.825 d20 18.926˜8.308˜0.874 <Fifth Lens UnitGr5-negative> r21 149.097 d21 1.080 N11 1.71300 ν11 53.93 r22 24.519 d221.540 r23 −121.815 d23 3.480 N12 1.67339 ν12 29.25 r24 −18.056 d24 1.130N13 1.75450 ν13 51.57 r25 ∞ Σd = 95.733˜93.328˜92.631

TABLE 4 << Embodiment 4 >> f = 82.6˜160.0˜234.0 FNO = 4.60˜5.90˜6.00Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 61.148 d1 1.700 N1 1.61293 ν1 36.96 r2 34.001d2 7.500 N2 1.49310 ν2 83.58 r3 −253.109 d3 0.100 r4 60.899 d4 4.200 N31.49310 ν3 83.58 r5 95.792 d5 3.300˜25.514˜41.021 <Second Lens UnitGr2-negative> r6 −85.359 d6 1.830 N4 1.71300 ν4 53.93 r7 26.983 d7 1.000r8 22.823 d8 1.215 N5 1.51728 ν5 69.43 r9 40.300 d9 2.500˜4.000˜7.500<Third Lens Unit Gr3-positive> r10 35.792 d10 1.215 N6 1.51728 ν6 69.43r11 21.684 d11 1.000 r12 29.241 d12 2.750 N7 1.67339 ν7 29.25 r13217.960 d13 29.529˜12.908˜1.306 <Aperture Diaphragm S, Fourth Lens UnitGr4-positive> r14 ∞ (Aperture Diaphragm S) d14 1.380 r15 55.422 d151.300 N8 1.84666 ν8 23.82 r16 27.905 d16 2.460 r17 47.314 d17 2.840 N91.51680 ν9 64.20 r18 −83.181 d18 0.400 r19 34.948 d19 4.550 N10 1.51680ν10 64.20 r20 −47.390 d20 17.734˜8.310˜0.874 <Fifth Lens UnitGr5-negative> r21 198.738 d21 1.080 N11 1.71300 ν11 53.93 r22 24.489 d221.540 r23 −114.315 d23 3.480 N12 1.67339 ν12 29.25 r24 −17.995 d24 1.130N13 1.75450 ν13 51.57 r25 ∞ Σd = 95.734˜93.403˜93.372

TABLE 5 |fL/fW| |f2/fW| f1/fW MT/MW Embodiment 1 0.345 1.58  1.00 1.72Embodiment 2 0.319 0.445 0.87 1.86 Embodiment 3 0.347 0.493 1.06 2.02Embodiment 4 0.332 0.487 1.06 2.00

TABLE 6 << Embodiment 5 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.31˜5.73Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 108.1551 d1 1.300 N1 1.83350 ν1 21.00 r251.344 d2 6.550 N2 1.58913 ν2 61.11 r3 −227.303 d3 0.100 r4 26.595 d44.250 N3 1.71300 ν3 53.93 r5 50.796 d5 1.845˜14.212˜19.892 <Second LensUnit Gr2-negative> r6 42.937 d6 1.100 N4 1.80420 ν4 46.50 r7 10.592 d74.400 r8 −30.198 d8 0.950 N5 1.75450 ν5 51.57 -- DL r9 23.104 d9 0.300r10 18.296 d10 3.700 N6 1.75000 ν6 25.14 r11 −41.997 d11 0.940 r12−15.369 d12 1.300 N7 1.69680 ν7 56.47 r13 −55.424 d13 10.978˜5.009˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 r15 24.823 d15 3.310 N8 1.62041 ν8 60.29 r16−28.498 d16 0.110 r17 25.329 d17 4.710 N9 1.51742 ν9 52.15 r18 −12.652d18 1.360 N10 1.80741 ν10 31.59 r19 134.710 d19 5.300˜1.349˜1.000<Fourth Lens Unit Gr5-positive> r20 40.082 d20 4.820 N11 1.51823 ν1158.96 r21 −17.987 d21 1.470 r22* −140.644 d22 0.100 N12 1.51790 ν1252.31 r23 −57.516 d23 1.400 N13 1.80500 ν13 40.97 r24 40.734 Σd =60.793˜63.239˜65.562 [Aspherical Coefficient] r22: ε = 1.0000 A4 =−0.10470 × 10³ A6 = −0.34309 × 10⁶ A8 = −0.53396 × 10⁹ A10 = −0.14576 ×10¹⁰ A12 = −0.69539 × 10¹⁵

TABLE 7 << Embodiment 6 >> f = 30.6˜64.7˜165.1 FNO = 4.60˜5.23˜5.81Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 89.595 d1 1.530 N1 1.84666 ν1 23.82 r2 50.523d2 6.970 N2 1.58913 ν2 61.11 r3 885.692 d3 0.127 r4 47.852 d4 5.695 N31.51680 ν3 64.20 r5 218.621 d5 0.467˜17.796˜41.243 <Second Lens UnitGr2-negative> r6 73.128 d6 1.020 N4 1.85000 ν4 40.04 r7 14.317 d7 4.420r8 −404.817 d8 2.550 N5 1.75000 ν5 25.14 r9 −31.873 d9 1.020 N6 1.77250ν6 49.77 r10 36.869 d10 1.105 r11 22.548 d11 2.635 N7 1.76182 ν7 26.55r12 212.813 d12 1.530 r13 −45.353 d13 1.000 N8 1.75450 ν8 51.57 -- DLr14 38.340 d14 1.000 N9 1.80518 ν9 25.43 -- DL r15 171.510 d1517.275˜8.731˜1.714 <Aperture Diaphragm S, Third Lens Unit Gr3-positive>r14 ∞ (Aperture Diaphragm S) d16 1.062 r17 33.590 d17 2.125 N10 1.51680ν10 64.20 r18 145.888 d18 0.085 r19 28.299 d19 2.720 N11 1.51823 ν1158.96 r20 −4683.183 d20 0.127 r21 40.246 d21 2.380 N12 1.51680 ν12 64.20r22 −101.132 d22 2.125 r23 −26.751 d23 1.020 N13 1.84666 ν13 23.82 r24397.583 d24 4.505˜1.969˜1.360 <Fourth Lens Unit Gr5-positive> r25 43.689d25 2.550 N14 1.51823 ν14 58.96 r26 −52.186 d26 0.127 r27 35.901 d272.890 N15 1.51823 ν15 58.96 r28 −32.031 d28 3.187 r29* −70.884 d29 0.030N16 1.51790 ν16 52.31 r30 −58.398 d30 1.190 N17 1.85000 ν17 40.04 r3123.219 d31 1.020 r32 68.181 d32 2.550 N18 1.67339 ν18 29.25 r33 −66.682d33 1.700˜9.782˜0.628 <Fifth Lens Unit Gr5-negative> r34 −41.406 d341.598 N19 1.67000 ν19 57.07 r35 −98.910 Σd = 81.338−95.669−102.335[Aspherical Coefficient] r29: ε = 1.0000 A4 = −0.68521 × 10⁴ A6 =−0.10299 × 10⁶ A8 = −0.23092 × 10⁸ A10 = −0.11744 × 10⁹ A12 = −0.13601 ×10¹¹

TABLE 8 << Embodiment 7 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.31˜5.73Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 122.692 d1 1.300 N1 1.83350 ν1 21.00 r251.521 d2 6.550 N2 1.58913 ν2 61.11 r3 −185.231 d3 0.100 r4 27.634 d44.250 N3 1.71300 ν3 53.93 r5 57.348 d5 1.845˜12.466˜19.246 <Second LensUnit Gr2-negative> r6 51.452 d6 1.100 N4 1.80420 ν4 46.50 r7 10.185 d74.400 r8 −30.276 d8 0.950 N5 1.75450 ν5 51.57 r9 20.585 d9 0.300 r1016.780 d10 3.700 N6 1.75000 ν6 25.14 r11 −38.497 d11 0.940 r12 −14.318d12 1.300 N7 1.69680 ν7 56.47 r13 −47.972 d13 9.859˜4.319˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 r15 32.322 d15 1.500 N8 1.62041 ν8 60.29 -- DLr16* −24.847 d16 0.500 r17* −24.847 d17 1.310 N9 1.62041 ν9 60.29 r18−24.706 d18 0.110 r19 24.077 d19 4.710 N10 1.51742 ν10 52.15 r20 −12.877d20 1.360 N11 1.80741 ν11 31.59 r21 133.539 d21 5.300˜1.467˜1.000<Fourth Lens Unit Gr5-positive> r22 35.194 d22 4.820 N12 1.51823 ν1258.96 r23 −17.079 d23 1.470 r24* −125.833 d24 0.100 N13 1.51790 ν1352.31 r25 −56.309 d25 1.400 N14 1.80500 ν14 40.97 r26 39.727 Σd =59.674˜60.923˜64.916 [Aspherical Coefficient] r16: ε = 1.0000 A4 =0.33000 × 10⁻⁴ r17: ε = 1.0000 A4 = 0.33000 × 10⁻⁴ r24: ε = 1.0000 A4 =−0.10469 × 10⁻³ A6 = −0.34301 × 10⁻⁶ A8 = −0.53437 × 10⁻⁹ A10 = −0.14584× 10⁻¹⁰ A12 = −0.75981 × 10⁻¹⁵

TABLE 9 << Embodiment 8 >> f = 22.6˜47.2˜80.7 FNO = 3.57˜4.38˜4.63Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 701.858 d1 1.339 N1 1.84666 ν1 23.78 r250.822 d2 6.300 N2 1.61272 ν2 58.75 r3 −142.661 d3 0.118 r4 33.789 d43.937 N3 1.83400 ν3 37.17 r5 86.386 d5 1.696˜13.804˜21.178 <Second LensUnit Gr2-negative> r6 39.339 d6 1.102 N4 1.83400 ν4 37.17 r7 11.226 d74.804 r8 −26.223 d8 2.126 N5 1.78472 ν5 25.68 r9 −15.872 d9 1.024 N61.77250 ν6 49.60 r10 41.165 d10 0.118 r11 22.587 d11 3.071 N7 1.78472 ν725.68 r12 −27.632 d12 1.102 r13 −18.584 d13 1.024 N8 1.81554 ν8 44.36r14 321.763 d14 9.368˜4.115˜1.069 <Aperture Diaphragm S, Third Lens UnitGr3-positive> r15 ∞ (Aperture Diaphragm S) d15 1.496 r16 29.194 d163.465 N9 1.61800 ν9 63.39 r17 −40.669 d17 0.079 r18 27.739 d18 5.591 N101.56873 ν10 63.16 r19 −14.928 d19 1.181 N11 1.83400 ν11 37.17 r20102.907 d20 7.384˜3.742˜2.663 <Fourth Lens Unit Gr4-positive> r21 24.467d21 2.362 N12 1.58170 ν12 69.75 -- DL r22* −59.882 d22 0.354 r23*−59.882 d23 1.575 N13 1.75450 ν13 51.57 r24 −27.635 d24 2.756 r25*−86.973 d25 1.488 N14 1.74500 ν14 34.96 r26 34.087 Σd =64.862˜68.073˜71.323 [Aspherical Coefficient] r22: ε = 1.0000 A4 =0.27748 × 10⁻⁴ r23: ε = 1.0000 A4 = 0.25095 × 10⁻⁴ r25: ε = 1.0000 A4 =−0.76769 × 10⁻⁴ A6 = −0.21795 × 10⁻⁶ A8 = 0.57736 × 10⁻⁹ A10 = −0.52121× 10⁻¹¹ A12 = 0.27373 × 10⁻¹³

TABLE 10 << Embodiment 9 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.45˜6.20Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 69.769 d1 1.300 N1 1.83350 ν1 21.00 r2 45.196d2 6.550 N2 1.58913 ν2 61.11 r3 −397.682 d3 0.100 r4 36.176 d4 4.250 N31.71300 ν3 53.93 r5 44.734 d5 1.845˜14.591˜25.237 <Second Lens UnitGr2-negative> r6 123.224 d6 1.100 N4 1.80420 ν4 46.50 r7 11.538 d7 4.400r8 −72.748 d8 0.950 N5 1.75450 ν5 51.57 r9 26.505 d9 0.300 r10 17.282d10 3.700 N6 1.75000 ν6 25.14 r11 −51.639 d11 0.940 r12 −28.103 d121.300 N7 1.69680 ν7 56.47 -- DL r13 64.162 d13 10.332˜3.957˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 r15 21.611 d15 3.310 N8 1.62041 ν8 60.29 r16−68.274 d16 0.110 r17 24.544 d17 4.710 N9 1.51742 ν9 52.15 r18 −13.473d18 1.360 N10 1.80741 ν10 31.59 r19 80.836 d19 5.300˜2.063˜1.000 <FourthLens Unit Gr4-positive> r20 27.647 d20 4.820 N11 1.51823 ν11 58.96 r21−19.138 d21 1.470 r22* 1610.591 d22 0.100 N12 1.51790 ν12 52.31 r23−292.156 d23 1.400 N13 1.80500 ν13 40.97 r24 42.444 Σd =60.147˜63.282˜70.907 [Aspherical Coefficient] r22: ε = 1.0000 A4 =−0.10446 × 10⁻³ A6 = −0.34881 × 10⁻⁶ A8 = −0.56963 × 10⁻⁹ A10 = −0.14711× 10⁻¹⁰ A12 = −0.89025 × 10⁻¹⁵

TABLE 11 D/f f1/fW fR/fW [W] [T] |Pd|/fW Embodiment 5 2.31 0.831 0.760.11 0.73 Embodiment 6 2.71 0.853 0.56 0.01 0.60 Embodiment 7 2.29 0.8250.02 0.01 0.99 Embodiment 8 2.65 0.876 0.85 0.18 0.74 Embodiment 9 3.480.897 0.46 0.03 0.81

TABLE 12 << Embodiment 10 >> f = 82.2˜160.0˜233.6 FNO = 4.60˜5.81˜6.19Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 100.722 d1 1.700 N1 1.61293 ν1 36.96 r249.221 d2 6.460 N2 1.49310 ν2 83.58 r3 −1678.106 d3 0.100 r4 56.111 d43.820 N3 1.49310 ν3 83.58 r5 859.262 d5 3.300˜27.890˜41.425 <Second LensUnit Gr2-negative> {Front Lens Unit GrA-Image Blur Compensating LensUnit} r6 −69.399 d6 1.830 N4 1.71300 ν4 53.93 r7 34.412 d7 3.000 r838.193 d8 2.750 N5 1.67339 ν5 29.25 r9 1893.115 d9 2.000 r10 −35.714 d101.215 N6 1.51728 ν6 69.43 r11 −29.097 d11 2.000 {Rear Lens Unit GrB} r12−24.999 d12 1.215 N7 1.51728 ν7 69.43 r13 −30.588 d13 20.004˜4.713˜1.036<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 1.380 r15 60.855 d15 1.300 N8 1.84666 ν8 23.82 r1626.095 d16 2.460 r17 41.450 d17 2.840 N9 1.51680 ν9 64.20 r18 −111.975d18 0.400 r19 35.623 d19 4.550 N10 1.51680 ν10 64.20 r20 −42.960 d2020.260˜9.024˜0.874 <Fourth Lens Unit Gr4-negative> r21 206.481 d21 1.080N11 1.71300 ν11 53.93 r22 24.106 d22 1.540 r23 −195.003 d23 3.480 N121.67339 ν12 29.25 r24 −18.789 d24 1.130 N13 1.75450 ν13 51.57 r25 ∞ Σd =89.815˜87.878˜89.586

TABLE 13 << Embodiment 11 >> f = 82.2˜160.0˜233.6 FNO = 4.60˜5.81˜6.60Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 103.105 d1 1.700 N1 1.61293 ν1 36.96 r247.562 d2 6.460 N2 1.49310 ν2 83.58 r3 −214.862 d3 0.100 r4 50.735 d43.820 N3 1.49310 ν3 83.58 r5 247.066 d5 3.300˜25.679˜34.769 <Second LensUnit Gr2-negative> {Front Lens Unit GrA-Image Blur Compensating LensUnit} r6 −70.232 d6 1.830 N4 1.71300 ν4 53.93 r7 33.675 d7 1.000 r820.095 d8 2.000 N5 1.51728 ν5 69.43 r9 24.008 d9 2.000 {Rear Lens UnitGrB} r10 30.117 d10 1.215 N6 1.51728 ν6 69.43 r11 19.468 d11 1.000 r1227.326 d12 2.750 N7 1.67339 ν7 29.25 r13 157.462 d13 22.913˜7.665˜1.036<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 1.380 r15 86.768 d15 1.300 N8 1.84666 ν8 23.82 r1628.577 d16 2.460 r17 46.617 d17 2.840 N9 1.51680 ν9 64.20 r18 −58.745d18 0.400 r19 34.744 d19 4.550 N10 1.51680 ν10 64.20 r20 −42.470 d2018.566˜7.464˜0.874 <Fourth Lens Unit Gr4-negative> r21 488.716 d21 1.080N11 1.71300 ν11 53.93 r22 24.791 d22 1.540 r23 −153.247 d23 3.480 N121.67339 ν12 29.25 r24 −17.314 d24 1.130 N13 1.75450 ν13 51.57 r25 ∞ Σd =88.815˜84.843˜80.715

TABLE 14 << Embodiment 12 >> f = 82.2˜160.0˜233.6 FNO = 4.60˜5.81˜6.12Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 113.986 d1 1.700 N1 1.61293 ν1 36.96 r253.568 d2 6.460 N2 1.49310 ν2 83.58 r3 −277.902 d3 0.100 r4 51.402 d43.820 N3 1.49310 ν3 83.58 r5 313.208 d5 3.300˜26.254˜39.244 <Second LensUnit Gr2-negative> {Front Lens Unit GrA} r6 −58.146 d6 1.830 N4 1.71300ν4 53.93 r7 36.289 d7 1.000 r8 29.826 d8 1.215 N5 1.51728 ν5 69.43 r948.766 d9 2.500 {Rear Lens Unit GrB-Image Blur Compensating Lens Unit}r10 61.169 d10 1.215 N6 1.51728 ν6 69.43 r11 29.572 d11 1.000 r12 36.154d12 2.750 N7 1.67339 ν7 29.25 r13 −598.254 d13 22.097˜5.758˜1.036<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 1.380 r15 72.175 d15 1.300 N8 1.84666 ν8 23.82 r1625.379 d16 2.460 r17 49.093 d17 2.840 N9 1.51680 ν9 64.20 r18 −82.965d18 0.400 r19 29.756 d19 4.550 N10 1.51680 ν10 64.20 r20 −40.741 d2019.667˜8.830˜0.874 <Fourth Lens Unit Gr4-negative> r21 170.677 d21 1.080N11 1.71300 ν11 53.93 r22 22.780 d22 1.540 r23 −161.563 d23 3.480 N121.67339 ν12 29.25 r24 −17.326 d24 1.130 N13 1.75450 ν13 51.57 r25 ∞ Σd =88.815˜84.593˜84.906

TABLE 15 << Embodiment 13 >> f = 82.2˜160.0˜233.6 FNO = 4.69˜5.81˜6.03Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 106.492 d1 1.700 N1 1.61293 ν1 36.96 r250.420 d2 6.460 N2 1.49310 ν2 83.58 r3 −246.009 d3 0.100 r4 49.684 d43.820 N3 1.49310 ν3 83.58 r5 239.154 d5 3.300˜26.710˜38.554 <Second LensUnit Gr2-negative> {Front Lens Unit GrA} r6 −61.101 d6 1.830 N4 1.71300ν4 53.93 r7 48.903 d7 4.000 {Rear Lens Unit GrB-Image Blur CompensatingLens Unit} r8 59.747 d8 1.215 N5 1.51728 ν5 69.43 r9 30.253 d9 1.000 r1037.070 d10 2.750 N6 1.67339 ν6 29.25 r11 −570.337 d11 22.350˜6.417˜1.036<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r12 ∞ (ApertureDiaphragm S) d12 1.380 r13 75.177 d13 1.300 N7 1.84666 ν7 23.82 r1425.910 d14 2.460 r15 49.949 d15 2.840 N8 1.51680 ν8 64.20 r16 −80.657d16 0.400 r17 31.812 d17 4.550 N9 1.51680 ν9 64.20 r18 −37.178 d1820.130˜8.855˜0.874 <Fourth Lens Unit Gr4-negative> r19 183.147 d19 1.080N10 1.71300 ν10 53.93 r20 23.293 d20 1.540 r21 −137.477 d21 3.480 N111.67339 ν11 29.25 r22 −17.437 d22 1.130 N12 1.75450 ν12 51.57 r23 ∞ Σd =88.815˜85.017˜83.500

TABLE 16 << Embodiment 14 >> f = 80.2˜235.1˜305.9 FNO = 4.60˜6.50˜6.90Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 158.114 d1 1.955 N1 1.85000 ν1 40.04 r268.648 d2 6.255 N2 1.49310 ν2 83.58 r3 −154.056 d3 0.156 r4 57.897 d43.597 N3 1.48749 ν3 70.44 r5 184.014 d5 3.127˜51.345˜64.591 <Second LensUnit Gr2-negative> {Front Lens Unit GrA-Image Blur Compensating LensUnit} r6 −58.146 d6 0.391 N4 1.69680 ν4 56.47 r7 21.988 d7 2.033 N51.75520 ν5 27.51 r8* 36.559 d8 2.619 {Rear Lens Unit GrB} r9* 41.898 d91.877 N6 1.61800 ν6 63.39 r10 −157.007 d10 39.082˜8.439˜1.564 <ApertureDiaphragm S, Third Lens Unit Gr3-positive> r11 ∞ (Aperture Diaphragm S)d11 1.407 r12 −923.532 d12 1.173 N7 1.84666 ν7 23.83 r13 38.530 d132.111 r14 189.888 d14 2.346 N8 1.59270 ν8 35.45 r15 −66.538 d15 1.095r16 63.084 d16 1.877 N9 1.51680 ν9 64.20 r17 −240.098 d17 0.078 r1839.252 d18 3.518 N10 1.48749 ν10 70.44 r19 −48.315 d1924.727˜7.153˜0.782 <Fourth Lens Unit Gr4-negative> r20 212.197 d20 0.938N11 1.75450 ν11 51.57 r21 27.379 d21 2.580 r22 −171.245 d22 2.502 N121.67339 ν12 29.25 r23 −20.480 d23 0.938 N13 1.69680 ν13 56.47 r24370.701 Σd = 106.383˜106.383˜106.383 [Aspherical Coefficient] r8: ε =1.0000 A4 = −0.61121 × 10⁻⁵ r9: ε = 1.0000 A4 = −0.69911 × 10⁻⁵ A6 =0.95248 × 10⁻⁶ A8 = −0.51197 × 10⁻¹⁰ A10 = −0.48524 × 10⁻¹² A12 =0.38472 × 10⁻¹⁴

TABLE 17 << Embodiment 15 >> f = 30.6˜64.7˜165.1 FNO = 4.60˜5.23˜5.81Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 89.595 d1 1.530 N1 1.84666 ν1 23.82 r2 50.523d2 6.970 N2 1.58913 ν2 61.11 r3 885.692 d3 0.127 r4 47.852 d4 5.695 N31.51680 ν3 64.20 r5 218.621 d5 0.467˜17.796˜41.243 <Second Lens UnitGr2-negative> {Front Lens Unit GrA} r6 73.128 d6 1.020 N4 1.85000 ν440.04 r7 14.317 d7 4.420 r8 −404.817 d8 2.550 N5 1.75000 ν5 25.14 r9−31.873 d9 1.020 N6 1.77250 ν6 49.77 r10 36.869 d10 1.105 r11 22.548 d112.635 N7 1.76182 ν7 26.55 r12 212.813 d12 1.530 {Rear Lens UnitGrB-Image Blur Compensating Lens Unit} r13 −45.353 d13 1.000 NB 1.75450ν8 51.57 r14 38.340 d14 1.000 N9 1.80518 ν9 25.43 r15 171.510 d1517.275˜8.731˜1.714 <Aperture Diaphragm S, Third Lens Unit Gr3-positive>r16 ∞ (Aperture Diaphragm S) d16 1.062 r17 33.590 d17 2.125 N10 1.51680ν10 64.20 r18 145.888 d18 0.085 r19 28.299 d19 2.720 N11 1.51823 ν1158.96 r20 −4683.183 d20 0.127 r21 40.246 d21 2.380 N12 1.51680 ν12 64.20r22 −101.132 d22 2.125 r23 −26.751 d23 1.020 N13 1.84666 ν13 23.82 r24397.583 d24 4.505˜1.969˜1.360 <Fourth Lens Unit Gr4-positive> r25 43.689d25 2.550 N14 1.51823 ν14 58.96 r26 −52.186 d26 0.127 r27 35.901 d272.890 N15 1.51823 ν15 58.96 r28 −32.031 d28 3.187 r29* −70.884 d29 0.030N16 1.51790 ν16 52.31 r30 −58.398 d30 1.190 N17 1.85000 ν17 40.04 r3123.219 d31 1.020 r32 68.181 d32 2.550 N18 1.67339 ν18 29.25 r33 −66.682d33 1.700˜9.782˜0.628 <Fifth Lens Unit Gr5-negative> r34 −41.406 d341.598 N19 1.67000 ν19 57.07 r35 −98.910 Σd = 81.338˜95.669˜102.335[Aspherical Coefficient] r29: ε = 1.0000 A4 = −0.68521 × 10⁻⁴ A6 =−0.10099 × 10⁻⁶ A8 = −0.23092 × 10⁻⁸ A10 = 0.11744 × 10⁻⁹ A12 = −0.13601× 10⁻¹¹

TABLE 18 (fT/fW) · (βLW/βLT) MT/MW Embodiment 10 1.71 1.78 Embodiment 111.60 1.92 Embodiment 12 1.68 2.29 Embodiment 13 1.70 2.33 Embodiment 142.00 2.52 Embodiment 15 4.70 2.53

TABLE 18 (fT/fW) · (βLW/βLT) MT/MW Embodiment 10 1.71 1.78 Embodiment 111.60 1.92 Embodiment 12 1.68 2.29 Embodiment 13 1.70 2.33 Embodiment 142.00 2.52 Embodiment 15 4.70 2.53

TABLE 20 << Embodiment 16 >> f = 30.6˜64.7˜165.1 FNO = 4.60˜5.23˜5.81Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 89.595 d1 1.530 N1 1.84666 ν1 23.82 r2 50.523d2 6.970 N2 1.58913 ν2 61.11 r3 885.692 d3 0.127 r4 47.852 d4 5.695 N31.51680 ν3 64.20 r5 218.621 d5 0.467˜17.796˜41.243 <Second Lens UnitGr2-negative> {Front Lens Unit GrA} r6 73.128 d6 1.020 N4 1.85000 ν440.04 r7 14.317 d7 4.420 r8 −404.817 d8 2.550 N5 1.75000 ν5 25.14 r9−31.873 d9 1.020 N6 1.77250 ν6 49.77 r10 36.869 d10 1.105 r11 22.548 d112.635 N7 1.76182 ν7 26.55 r12 212.813 d12 1.530 {Rear Lens UnitGrB-Image Blur Compensating Lens Unit} r13 −45.353 d13 1.000 N8 1.75450ν8 51.57 r14 38.340 d14 1.000 N9 1.80518 ν9 25.43 r15 171.510 d1517.275˜8.731˜1.714 <Aperture Diaphragm S, Third Lens Unit Gr3-positive>r16 ∞ (Aperture Diaphragm S) d16 1.062 r17 33.590 d17 2.125 N10 1.51680ν10 64.20 r18 145.888 d18 0.085 r19 28.299 d19 2.720 N11 1.51823 ν1158.96 r20 −4683.183 d20 0.127 r21 40.246 d21 2.380 N12 1.51680 ν12 64.20r22 −101.132 d22 2.125 r23 −26.751 d23 1.020 N13 1.84666 ν13 23.82 r24397.583 d24 4.505˜1.969˜1.360 <Fourth Lens Unit Gr4-positive> r25 43.689d25 2.550 N14 1.51823 ν14 58.96 r26 −52.186 d26 0.127 r27 35.901 d272.890 N15 1.51823 ν15 58.96 r28 −32.031 d28 3.187 r29* −70.884 d29 0.030N16 1.51790 ν16 52.31 r30 −58.398 d30 1.190 N17 1.85000 ν17 40.04 r3123.219 d31 1.020 r32 68.181 d32 2.550 N18 1.67339 ν18 29.25 r33 −66.682d33 1.700˜9.782˜0.628 <Fifth Lens Unit Gr5-negative> r34 −41.406 d341.598 N19 1.67000 ν19 57.07 r35 −98.910 Σd = 81.338˜95.669˜102.335[Aspherical Coefficient] r29: ε = 1.0000 A4 = −0.68521 × 10⁻⁴ A6 =−0.10299 × 10⁻⁶ A8 = −0.23092 × 10⁻⁸ A10 = 0.11744 × 10⁻⁹ A12 = −0.13601× 10⁻¹¹

TABLE 21 << Embodiment 17 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.31˜5.73Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 122.692 d1 1.300 N1 1.83350 ν1 21.00 r251.521 d2 6.550 N2 1.58913 ν2 61.11 r3 −185.231 d3 0.100 r4 27.634 d44.250 N3 1.71300 ν3 53.93 r5 57.348 d5 1.845˜12.466˜19.246 <Second LensUnit Gr2-negative> r6 51.452 d6 1.100 N4 1.80420 ν4 46.50 r7 10.185 d74.400 r8 −30.276 d8 0.950 N5 1.75450 ν5 51.57 r9 20.585 d9 0.300 r1016.780 d10 3.700 N6 1.75000 ν6 25.14 r11 −38.497 d11 0.940 r12 −14.318d12 1.300 N7 1.69680 ν7 56.47 r13 −47.972 d13 9.859˜4.319˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 {Front Lens Unit GrA-Image Blur Compensating LensUnit} r15 32.322 d15 1.500 N8 1.62041 ν8 60.29 r16* −24.847 d16 0.500{Rear Lens Unit GrB} r17* −24.847 d17 1.310 N9 1.62041 ν9 60.29 r18−24.706 d18 0.110 r19 24.077 d19 4.710 N10 1.51742 ν10 52.15 r20 −12.877d20 1.360 N11 1.80741 ν11 31.59 r21 133.539 d21 5.300˜1.467˜1.000<Fourth Lens Unit Gr4-positive> r22 35.194 d22 4.820 N12 1.51823 ν1258.96 r23 −17.079 d23 1.470 r24* −125.833 d24 0.100 N13 1.51790 ν1352.31 r25 −56.309 d25 1.400 N14 1.80500 ν14 40.97 r26 39.727 Σd =59.674˜60.923˜64.916 [Aspherical Coefficient] r16: ε = 1.0000 A4 =0.33000 × 10⁻⁴ r17: ε = 1.0000 A4 = 0.33000 × 10⁻⁴ r24: ε = 1.0000 A4 =−0.10469 × 10⁻³ A6 = −0.34301 × 10⁻⁶ A8 = −0.53437 × 10⁻⁹ A10 = −0.14584× 10⁻¹⁰ A12 = −0.75981 × 10⁻¹⁵

TABLE 22 << Embodiment 18 >> f = 22.6˜47.2˜80.7 FNO = 3.57˜4.38˜4.63Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 7010.858 d1 1.339 N1 1.84666 ν1 23.78 r250.822 d2 6.300 N2 1.61272 ν2 58.75 r3 −142.661 d3 0.118 r4 33.789 d43.937 N3 1.83400 ν3 37.17 r5 86.386 d5 1.696˜13.804˜21.178 <Second LensUnit Gr2-negative> r6 39.339 d6 1.102 N4 1.83400 ν4 37.17 r7 11.226 d74.804 r8 −26.223 d8 2.126 N5 1.78472 ν5 25.68 r9 −15.872 d9 1.024 N61.77250 ν6 49.60 r10 41.165 d10 0.118 r11 22.587 d11 3.071 N7 1.78472 ν725.68 r12 −27.632 d12 1.102 R13 −18.584 d13 1.024 N8 1.81554 ν8 44.36r14 321.763 d14 9.368˜4.115˜1.069 <Aperture Diaphragm S, Third Lens UnitGr3-positive> r15 ∞ (Aperture Diaphragm S) d15 1.496 r16 29.194 d163.465 N9 1.61800 ν9 63.39 r17 −40.669 d17 0.079 r18 27.739 d18 5.591 N101.56873 ν10 63.16 r19 −14.928 d19 1.181 N11 1.83400 ν11 37.17 r20102.907 d20 7.384˜3.742˜2.663 <Fourth Lens Unit Gr4-positive> {FrontLens Unit GrA-Image Blur Compensating Lens Unit} r21 24.467 d21 2.362N12 1.58170 ν12 69.75 r22* −59.882 d22 0.354 {Rear Lens Unit GrB} r23*59.882 d23 1.575 N13 1.75450 ν13 51.57 r24 −27.635 d24 2.756 r25*−86.973 d25 1.488 N14 1.74500 ν14 34.96 r26 34.087 Σd =64.862˜68.073˜71.323 [Aspherical Coefficient] r22: ε = 1.0000 A4 =0.27748 × 10⁻⁴ r23: ε = 1.0000 A4 = 0.25095 × 10⁻⁴ r25: ε = 1.0000 A4 =−0.76769 × 10⁻⁴ A6 = −0.21795 × 10⁻⁶ A8 = 0.57736 × 10⁻⁹ A10 = −0.52121× 10⁻¹¹ A12 = 0.27373 × 10⁻¹³

TABLE 23 << Embodiment 19 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.45˜6.20Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 69.769 d1 1.300 N1 1.83350 ν1 21.00 r2 45.196d2 6.550 N2 1.58913 ν2 61.11 r3 −397.682 d3 0.100 r4 36.176 d4 4.250 N31.71300 ν3 53.93 r5 44.734 d5 1.845˜14.591˜25.237 <Second Lens UnitGr2-negative> {Front Lens Unit GrA} r6 123.224 d6 1.1000 N4 1.80420 ν446.50 r7 11.538 d7 4.400 r8 −72.748 d8 0.950 N5 1.75450 ν5 51.57 r926.505 d9 0.300 r10 17.282 d10 3.700 N6 1.75000 ν6 25.14 r11 −51.639 d110.940 {Rear Lens Unit GrB-Image Blur Compensating Lens Unit} r12 −28.103d12 1.300 N7 1.69680 ν7 56.47 r13 64.162 d13 10.332˜3.957˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 r15 21.611 d15 3.310 N8 1.62041 ν8 60.29 r16−68.274 d16 0.110 r17 24.544 d17 4.710 N9 1.51742 ν9 52.15 r18 −13.473d18 1.360 N10 1.80741 ν10 31.59 r19 80.836 d19 5.300˜2.063˜1.000 <FourthLens Unit Gr4-positive> r20 27.647 d20 4.820 N11 1.51823 ν11 58.96 r21−19.138 d21 1.470 r22* 1610.591 d22 0.100 N12 1.51790 ν12 52.31 r23−292.156 d23 1.400 N13 1.80500 ν13 40.97 r24 42.444 Σd =60.147˜63.282˜70.907 [Aspherical Coefficient] r22: ε = 1.0000 A4 =0.10446 × 10⁻³ A6 = −0.34881 × 10⁻⁶ A8 = −0.56963 × 10⁻⁹ A10 = −0.14711× 10⁻¹⁰ A12 = −0.89025 × 10⁻¹⁵

TABLE 24 D/f f1/fW fR/fW [W] [T] |Pd|/fW Embodiment 16 2.71 0.853 0.560.01 0.60 Embodiment 17 2.29 0.825 0.02 0.01 0.99 Embodiment 18 2.650.876 0.85 0.18 0.74 Embodiment 19 3.48 0.897 0.46 0.03 0.81

TABLE 25 << Embodiment 20 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.31˜5.73Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 122.692 d1 1.300 N1 1.83350 ν1 21.00 r2 51.521 d2 6.550 N2 1.58913 ν2 61.11 r3 −185.231 d3 0.100 r4 27.634 d4 4.250N3 1.71300 ν3 53.93 r5 57.348 d5 1.845˜12.466˜19.246 <Second Lens UnitGr2-negative> r6 51.452 d6 1.100 N4 1.80420 ν4 46.50 r7 10.185 d7 4.400r8 −30.276 d8 0.950 N5 1.75450 ν5 51.57 r9 20.585 d9 0.300 r10 16.780d10 3.700 N6 1.75000 ν6 25.14 r11 −38.497 d11 0.940 r12 −14.318 d121.300 N7 1.69680 ν7 56.47 r13 −47.972 d13 9.859˜4.319˜2.000 <ApertureDiaphragm S, Third Lens Unit Gr3 - positive> r14 ∞ (Aperture DiaphragmS) d14 0.500 {Front Lens Unit GrA-Image Blur Compensating Lens Unit{ r1532.322 d15 1.500 N8 1.62041 ν8 60.29 r16* −24.847 d16 0.500 {Rear LensUnit GrB} r17* −24.847 d17 1.310 N9 1.62041 ν9 60.29 r18 −24.706 d180.110 r19 24.077 d19 4.710 N10 1.51742 ν10 52.15 r20 −12.877 d20 1.360N11 1.80741 ν11 31.59 r21 133.539 d21 5.300˜1.467˜1.000 <Fourth LensUnit Gr4-positive> r22 35.194 d22 4.820 N12 1.51823 ν12 58.96 r23−17.079 d23 1.470 r24* −125.833 d24 0.100 N13 1.51790 ν13 52.31 r25−56.309 d25 1.400 N14 1.80500 ν14 40.97 r26 39.727 Σd =59.674˜60.923˜64.916 [Aspherical Coefficient] r16: ε = 1.0000 A4 =0.33000 × 10⁻⁴ r17: ε = 1.0000 A4 = 0.33000 × 10⁻⁴ r24: ε = 1.0000 A4 =−0.10469 × 10⁻³ A6 = −0.34301 × 10⁻⁶ A8 = −0.53437 × 10⁻⁹ A10 = 0.14584× 10⁻¹⁰ A12 = −0.75981 × 10⁻¹⁵

TABLE 26 << Embodiment 21 >> f = 22.6˜47.2˜80.7 FNO = 3.57˜4.38˜4.63Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 701.858 d1 1.339 N1 1.84666 ν1 23.78 r250.822 d2 6.300 N2 1.61272 ν2 58.75 r3 −142.661 d3 0.118 r4 33.789 d43.937 N3 1.83400 ν3 37.17 r5 86.386 d5 1.696˜13.804˜21.178 <Second LensUnit Gr2-negative> r6 39.339 d6 1.102 N4 1.83400 ν4 37.17 r7 11.226 d74.804 r8 −26.223 d8 2.126 N5 1.78472 ν5 25.68 r9 −15.872 d9 1.024 N61.77250 ν6 49.60 r10 41.165 d10 0.118 r11 22.587 d11 3.071 N7 1.78472 ν725.68 r12 −27.632 d12 1.102 r13 −18.584 d13 1.024 N8 1.81554 ν8 44.36r14 321.763 d14 9.368˜4.115˜1.069 <Aperture Diaphragm S, Third Lens UnitGr3-positive> r15 ∞ (Aperture Diaphragm S) d15 1.496 r16 29.194 d163.465 N9 1.61800 ν9 63.39 r17 −40.669 d17 0.079 r18 27.739 d18 5.591 N101.56873 ν10 63.16 r19 −14.928 d19 1.181 N11 1.83400 ν11 37.17 r20102.907 d20 7.384˜3.742˜2.663 <Fourth Lens Unit Gr4-positive> {FrontLens Unit GrA-Image Blur Compensating Lens Unit} r21 24.467 d21 2.362N12 1.58170 ν12 69.75 r22* −59.882 d22 0.354 {Rear Lens Unit GrB} r23*−59.882 d23 1.575 N13 1.75450 ν13 51.57 r24 −27.635 d24 2.756 r25*−86.973 d25 1.488 N14 1.74500 ν14 34.96 r26 34.087 Σd =64.862˜68.073˜71.323 [Aspherical Coefficient] r22: ε = 1.0000 A4 =0.27748 × 10⁻⁴ r23: ε = 1.0000 A4 = 0.25095 × 10⁻⁴ r25: ε = 1.0000 A4 =−0.76769 × 10⁻⁴ A6 = −0.21795 × 10⁻⁶ A8 = 0.57736 × 10⁻⁹ A10 = −0.52121× 10⁻¹¹ A12 = 0.27373 × 10⁻¹³

TABLE 27 << Embodiment 22 >> f = 22.6˜50.5˜78.0 FNO = 4.10˜5.45˜6.20Radius of Axial Refractive Abbe Curvature Distance Index Number <FirstLens Unit Gr1-positive> r1 69.769 d1 1.300 N1 1.83350 ν1 21.00 r2 45.196d2 6.550 N2 1.58913 ν2 61.11 r3 −397.682 d3 0.100 r4 36.176 d4 4.250 N31.71300 ν3 53.93 r5 44.734 d5 1.845˜14.591˜25.237 <Second Lens UnitGr2-negative> {Front Lens Unit GrA} r6 123.224 d6 1.100 N4 1.80420 ν446.50 r7 11.538 d7 4.400 r8 −72.748 d8 0.950 N5 1.75450 ν5 51.57 r926.505 d9 0.300 r10 17.282 d10 3.700 N6 1.75000 ν6 25.14 r11 −51.639 d110.940 {Rear Lens Unit GrB-Image Blur Compensating Lens Unit} r12 −28.103d12 1.300 N7 1.69680 ν7 56.47 r13 64.162 d13 10.332˜3.957˜2.000<Aperture Diaphragm S, Third Lens Unit Gr3-positive> r14 ∞ (ApertureDiaphragm S) d14 0.500 r15 21.611 d15 3.310 N8 1.62041 ν8 60.29 r16−68.274 d16 0.110 r17 24.544 d17 4.710 N9 1.51742 ν9 52.15 r18 −13.473d18 1.360 N10 1.80741 ν10 31.59 r19 80.836 d19 5.300˜2.063˜1.000 <FourthLens Unit Gr4-positive> r20 27.647 d20 4.820 N11 1.51823 ν11 58.96 r21−19.138 d21 1.470 r22* 1610.591 d22 0.100 N12 1.51790 ν12 52.31 r23−292.156 d23 1.400 N13 1.80500 ν13 40.97 r24 42.444 Σd =60.147˜63.282˜70.907 [Aspherical Coefficient] r22: ε = 1.0000 A4 =−0.10446 × 10⁻³ A6 = −0.34881 × 10⁻⁶ A8 = −0.56963 × 10⁻⁹ A10 = −0.14711× 10⁻¹⁰ A12 = −0.89025 × 10⁻¹⁵

TABLE 28 D/f f1/fW fR/fW [W] [T] |Pd|/fW Embodiment 20 2.29 0.825 0.020.01 0.99 Embodiment 21 2.65 0.876 0.85 0.18 0.74 Embodiment 22 3.480.897 0.46 0.03 0.81

What is claimed is:
 1. A zoom lens system comprising from an objectside: a first lens unit having a positive refractive power, said firstlens unit being moved toward the object side during zooming from awide-angle limit to a telephoto limit; a second lens unit having anegative refractive power; a third lens unit having a positiverefractive power; and a fourth lens unit having a positive refractivepower, said fourth lens unit being moved toward the object side duringzooming from the wide-angle limit to the telephoto limit, wherein oneimage blur compensating single lens element in any of the second tofourth lens units is moved vertically to an optical axis to compensatefor an image blur, and wherein the following condition is fulfilled:0.75<|fR/fW|<1.8 where fR is a composite focal length of the third lensunit and the entire lens units provided at an image side of the thirdlens unit at the wide-angle limit, and fW is a focal length of theentire zoom lens system at the wide-angle limit.
 2. A zoom lens systemas claimed in claim 1, wherein the second lens unit includes the imageblur compensating lens element.
 3. A zoom lens system as claimed inclaim 1, wherein the third lens unit includes the image blurcompensating lens element.
 4. A zoom lens system as claimed in claim 1,wherein the fourth lens unit includes the image blur compensating lenselement.
 5. A zoom lens system as claimed in claim 1, wherein said imageblur compensating lens is a doublet lens formed of a positive lens and anegative lens.
 6. A zoom lens system as claimed in claim 1, wherein saidzoom lens system has an aperture diagram, and fulfills the followingcondition: D/f<1.2 where D is a distance from an aperture diaphragm sidesurface of the image blur compensating lens element to the aperturediaphragm, and f is a focal length of the entire zoom lens system.
 7. Azoom lens system as claimed in claim 1, further fulfilling the followingcondition: |Pd|/fW<2.30 where Pd is a refractive power of the image blurcompensating lens element.
 8. A zoom lens system as claimed in claim 1,wherein overall refractive power of the image blur compensating lenselement is positive, said image blur compensating lens element being adoublet lens formed of a positive lens element and a negative lenselement, and fulfilling the following condition: νp>νn where νp is anAbbe number of the positive lens element, and νn is an Abbe number ofthe negative lens element.
 9. A zoom lens system as claimed in claim 1,wherein overall refractive power of the image blur compensating lenselement is negative, said image blur compensating lens element being adoublet lens formed of a positive lens element and a negative lenselement, and fulfilling the following condition: νp<νn where νp is anAbbe number of the positive lens element, and νn is an Abbe number ofthe negative lens element.
 10. A zoom lens system comprising from anobject side: a first lens unit having a positive refractive power, saidfirst lens unit being moved toward the object side during zooming from awide-angle limit to a telephoto limit; a second lens unit having anegative refractive power; a third lens unit having a positiverefractive power; and a fourth lens unit having a positive refractivepower, wherein any of the second lens unit and lens units disposed on animage side of the second lens unit comprises from the object side afront lens and a rear lens unit, either said front lens unit or saidrear lens unit being moved vertically to an optical axis to compensatefor an image blur, wherein a distance between said front and rear lensunits is fixed during zooming, wherein the following condition isfulfilled: 2.1<f1/fW<4.3 where f1 is a focal length of the first lensunit, and fW is a focal length of the entire zoom lens system at thewide-angle limit.
 11. A zoom lens system as claimed in claim 10, whereinthe front lens unit and the rear lens unit are included in the secondlens unit.
 12. A zoom lens system as claimed in claim 10, wherein thefront lens unit and the rear lens unit are included in the third lensunit.
 13. A zoom lens system as claimed in claim 10, wherein the frontlens unit and the rear lens unit are included in the fourth lens unit.14. A zoom lens system as claimed in claim 10, wherein each of the firstthrough fourth lens units are moved during a zooming mode of operationand one of the first lens units and rear lens units are maintainedstationary during compensation for image blur.
 15. A zoom lens systemcomprising from an object side: a first lens unit having a positiverefractive power, said first lens unit being moved toward the objectside during zooming from a wide-angle limit to a telephoto limit; asecond lens unit having a negative refractive power; a third lens unithaving a positive refractive power; and a fourth lens unit, wherein anyof the second lens unit and lens units disposed on an image side of thesecond lens unit comprises, from the object side, a front lens unit anda rear lens unit, either said front or said rear lens unit being movedvertically from an optical axis to compensate for an image blur, whereinthe following condition is fulfilled: 2.1<f1/fW<4.3 where F1 is a focallength of the first lens unit, and fW is a focal length of the entirezoom lens system at the wide-angle limit.
 16. A zoom lens system asclaimed in claim 15, wherein said zoom lens system has an aperturediaphragm and fulfills the following condition: D/f<1.2 where D is adistance from an aperture diaphragm side surface either of the front orthe rear lens unit moving vertically to an optical axis to compensatefor an image blur to the aperture diaphragm, and f is a focal length ofthe entire zoom lens system.
 17. A zoom lens system as claimed in claim15, further fulfilling the following condition: |Pd|/fW<2.30 where Pd isa refractive power either of the front or the rear lens unit movingvertically to an optical axis to compensate for an image blur.
 18. Azoom lens system as claimed in claim 15, wherein either of the front orthe rear lens unit moving vertically to an optical axis to compensatefor an image blur is a doublet lens formed of a positive lens elementand a negative lens element, said doublet lens having a positiverefractive power, said doublet lens fulfilling the following conditions:νp>νn where νp is an Abbe number of a positive lens element, νn is anAbbe number of a negative lens element.
 19. A zoom lens system asclaimed in claim 15, wherein either of the front or the rear lens unitmoving vertically to an optical axis to compensate for an image blur isa doublet lens formed of a positive lens element and a negative lenselement, said doublet lens having a negative refractive power, saiddoublet lens fulflling the following conditions: νp<νn where νp is anAbbe number of a positive lens element, νn is an Abbe number of anegative lens element.
 20. A zoom lens system comprising from an objectside: a first lens unit having a positive refractive power, said firstlens unit being moved toward the object side during zooming from awide-angle limit to a telephoto limit; a second lens unit having anegative refractive power, said second lens unit comprising from theobject side a front lens unit and a rear lens unit, either said frontlens unit or said rear lens unit being moved vertically to an opticalaxis to compensate for an image blur, a distance between said front andrear lens units being fixed during zooming and the front or the rearlens unit which is moved vertically to the optical axis to compensatefor image blur has at least one positive lens element and at least onenegative lens element; a third lens unit having a positive refractivepower; and a fourth lens unit having a negative refractive power,wherein the following condition is fulfilled: 0.4<MT/MW<2.5 wherein MTis a blur compensation movement amount of the second lens unit at thetelephoto limit, and MW is a blur compensation movement amount of thesecond lens unit at the wide-angle limit.
 21. A zoom lens system asclaimed in claim 20, further comprising the following condition: νp>νnwhere νp is an Abbe number of a positive lens included in the secondlens unit, and νn is an Abbe number of a negative lens included in thesecond lens unit.
 22. A zoom lens system as claimed in claim 21, furthercomprising the following condition: 1.3<(fT/fW)·(βLW/βLT)<7.0 where fTis the focal length of the entire lens system at the telephoto limit, fWis the focal length of the entire lens system at the wide-angle limit,βLW is the magnification of the fourth lens unit at the wide-anglelimit, and βLT is the magnification of the fourth lens unit at thetelephoto limit.
 23. A zoom lens system as claimed in claim 22, whereinthe third lens unit includes an aperture stop and the third lens unitand the aperture stop is moved during zooming.